engine pressure JEEP GRAND CHEROKEE 2003 WJ / 2.G Workshop Manual

(5) Remove the (2) refrigerant line retaining bolts
that secure the suction line and discharge line to the
compressor. Install plugs in, or tape over all of the
opened refrigerant fittings.
(6) Remove the bolts that secure the compressor
(Fig. 2) or (Fig. 3) and (Fig. 4).
(7) Remove the compressor.
Fig. 2 COMPRESSOR REMOVE/INSTALL - 4.0L
ENGINE
1 - POWER STEERING PUMP MOUNTING BRACKET
2 - BOLT
3 - BRACE
4 - BOLT
5 - BOLT
6 - A/C COMPRESSOR
7 - BOLT
Fig. 3 COMPRESSOR AND A/C LINES - V8
1 - DISCHARGE LINE
2 - A/C COMPRESSOR
3 - SUCTION LINE
4 - A/C/ CONDENSOR
5 - DISCHARGE LINE TO CONDENSOR
6 - A/C PRESSURE TRANSDUCER SWITCH
7 - A/C/ SERVICE PORT
8 - RECEIVER DRIER
Fig. 4 COMPRESSOR REMOVE/INSTALL - V8
ENGINE - RIGHT VIEW
1 - BOLT
2 - A/C COMPRESSOR
3 - BOLT
WJPLUMBING 24 - 59
A/C COMPRESSOR (Continued)

STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE)
(8) Charge the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
(9) Connect the negative battery cable.
A/C CONDENSER
DESCRIPTION
The condenser is located in the air flow in front of
the engine cooling radiator. The condenser is a heat
exchanger that allows the high-pressure refrigerant
gas being discharged by the compressor to give up its
heat to the air passing over the condenser fins.
OPERATION
When the refrigerant gas gives up its heat, it con-
denses. When the refrigerant leaves the condenser, it
has become a high-pressure liquid refrigerant. The
volume of air flowing over the condenser fins is crit-
ical to the proper cooling performance of the air con-
ditioning system. Therefore, it is important that
there are no objects placed in front of the radiator
grille openings in the front of the vehicle or foreign
material on the condenser fins that might obstruct
proper air flow. Also, any factory-installed air seals or
shrouds must be properly reinstalled following radia-
tor or condenser service.
The condenser cannot be repaired and, if faulty or
damaged, it must be replaced.
REMOVAL
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS GROUP BEFORE
PERFORMING THE FOLLOWING OPERATION.
CAUTION: Before removing the condenser, note the
location of each of the radiator and condenser air
seals. These seals are used to direct air through the
condenser and radiator. The air seals must be rein-
stalled in their proper locations in order for the air
conditioning and engine cooling systems to per-
form as designed.(1) Disconnect and isolate the battery negative
cable.
(2) Recover the refrigerant from the refrigerant
system. (Refer to 24 - HEATING & AIR CONDI-
TIONING/PLUMBING - STANDARD PROCEDURE -
REFRIGERANT RECOVERY)
(3) Remove the screws attaching the grille and
headlamp mounting module to the upper crossmem-
ber of the vehicle. Refer to Body for this and further
steps in the procedure.
(4) Remove the headlamps from their mounts.
(5) Remove the nuts that secure the hood latch
and brace to the upper crossmember.
(6) The radiator upper crossmember can be
adjusted left or right through the use of its slotted
mounting holes. Before removal, mark the original
position of the crossmember.
(7) Remove the bolts that secure the radiator to
the upper crossmember and set it aside (Fig. 6).
(8) Remove the engine air filter inlet duct secured
at the headlamp mounting module.
(9) Remove the headlamp mounting module and
front fascia for access to the condenser and fittings.
(10) Disconnect the discharge line and liquid line
refrigerant line fittings from the condenser. Install
plugs in, or tape over all of the opened refrigerant
line fittings.Fig. 6 CONDENSER MOUNTING - TYPICAL
1 - CONDENSER-TO-RADIATOR MOUNTING BRACKETS (2)
2 - UPPER CROSSMEMBER
3 - FAN SHROUD
4 - ALIGNMENT TABS
5 - RADIATOR
6 - ALIGNMENT DOWELS (2)
7 - RUBBER ISOLATORS (2)
8 - RUBBER GROMMETS (2)
9 - LOWER CROSSMEMBER
10 - CONDENSER
24 - 62 PLUMBINGWJ
A/C COMPRESSOR (Continued)

(11) Remove the bolts that secure the upper con-
denser and transmission cooler.
(12) Carefully lift the condenser out of the vehicle.
INSTALLATION
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
Any kinks or sharp bends in the refrigerant plumb-
ing will reduce the capacity of the entire air condi-
tioning system. Kinks and sharp bends reduce the
flow of refrigerant in the system. A good rule for the
flexible hose refrigerant lines is to keep the radius of
all bends at least ten times the diameter of the hose.
In addition, the flexible hose refrigerant lines should
be routed so they are at least 80 millimeters (3
inches) from the exhaust manifold.
High pressures are produced in the refrigerant sys-
tem when the air conditioning compressor is operat-
ing. Extreme care must be exercised to make sure
that each of the refrigerant system connections is
pressure-tight and leak free. It is a good practice to
inspect all flexible hose refrigerant lines at least once
a year to make sure they are in good condition and
properly routed.
CAUTION: Before removing the condenser, note the
location of each of the radiator and condenser air
seals. These seals are used to direct air through the
condenser and radiator. The air seals must be rein-
stalled in their proper locations in order for the air
conditioning and engine cooling systems to per-
form as designed.
(1) Carefully position the condenser in the vehicle.
(2) Install the bolts that secure the upper con-
denser and transmission cooler.
(3) Remove the tape or plugs from the refrigerant
line fittings on the condenser inlet and the discharge
line. Connect the discharge line to the condenser
inlet. Tighten the retaining nut to 28 N´m (250 in.
lbs.).
(4) Remove the tape or plugs from the refrigerant
line fittings on the condenser outlet and the liquid
line. Connect the liquid line to the condenser outlet.
Tighten the retaining nut to 28 N´m (250 in. lbs.).
(5) Install the headlamp mounting module and
front fascia. Refer to Body for the procedure.
(6) Install the engine air filter inlet duct.
(7) Install the bolts that secure the radiator to the
upper crossmember.(8) Install the nuts that secure the hood latch and
brace to the upper crossmember.
(9) Install the headlamps in their mounts.
(10) Install the screws attaching the grille and
headlamp mounting module to the upper crossmem-
ber of the vehicle. Refer to Body for this and further
steps in the procedure.
(11) Evacuate and Recharge the refrigerant sys-
tem. (Refer to 24 - HEATING & AIR CONDITION-
ING/PLUMBING - STANDARD PROCEDURE -
REFRIGERANT SYSTEM EVACUATE) (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
(12) Connect the battery negative cable.
NOTE: If the condenser is replaced, add 30 millili-
ters (1 fluid ounce) of refrigerant oil to the refriger-
ant system. Use only refrigerant oil of the type
recommended for the compressor in the vehicle.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING/REFRIGERANT OIL - DESCRIPTION)
A/C DISCHARGE LINE
REMOVAL
REMOVAL - 2.7L TURBO DIESEL
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
(1) Disconnect and isolate the negative battery
cable.
(2) Recover the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT
RECOVERY)
(3) Remove both headlamps from the vehicle. Refer
to Lamps/Lighting for the procedure.
(4) Remove the a/c high pressure transducer(Refer
to 24 - HEATING & AIR CONDITIONING/CON-
TROLS/A/C PRESSURE TRANSDUCER - REMOV-
AL).
(5) Remove the front fascia from the vehicle. Refer
to Front Fascia for the procedure (Fig. 7).
(6) Remove the refrigerant line retaining fastener
from the condenser inlet fitting. Remove the line and
cap the condenser inlet tube to prevent contamina-
tion of the system.
WJPLUMBING 24 - 63
A/C CONDENSER (Continued)

ING & AIR CONDITIONING/CONTROLS/A/C
PRESSURE TRANSDUCER - INSTALLATION).
(9) Evacuate the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE)
(10) Charge the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
(11) Connect the negative battery cable.
INSTALLATION
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
Any kinks or sharp bends in the refrigerant plumb-
ing will reduce the capacity of the entire air condi-
tioning system. Kinks and sharp bends reduce the
flow of refrigerant in the system. A good rule for the
flexible hose refrigerant lines is to keep the radius of
all bends at least ten times the diameter of the hose.
In addition, the flexible hose refrigerant lines should
be routed so they are at least 80 millimeters (3
inches) from the exhaust manifold.
High pressures are produced in the refrigerant sys-
tem when the air conditioning compressor is operat-
ing. Extreme care must be exercised to make sure
that each of the refrigerant system connections is
pressure-tight and leak free. It is a good practice to
inspect all flexible hose refrigerant lines at least once
a year to make sure they are in good condition and
properly routed.
(1) Remove the tape or plugs from the discharge
line block fitting and the manifold on the compressor.
Install the discharge line block fitting to the manifold
on the compressor. Tighten the mounting bolt to 25.4
N´m (225 in. lbs.).
(2) Remove the tape or plugs from the refrigerant
line fittings on the condenser inlet and the discharge
line. Connect the discharge line to the condenser
inlet. Tighten the retaining nut to 28 N´m (250 in.
lbs.).
(3) Install the a/c high pressure transducer(Refer
to 24 - HEATING & AIR CONDITIONING/CON-
TROLS/A/C PRESSURE TRANSDUCER - INSTAL-
LATION).
(4) Connect the battery negative cable.
(5) Evacuate the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE)(6) Charge the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
A/C EXPANSION VALVE
DESCRIPTION
The ªHº valve type thermal expansion valve (TXV)
is located at the front of the heater-A/C housing
between the liquid and suction lines and the evapo-
rator coil.
The expansion valve is a factory calibrated unit
and cannot be adjusted or repaired. If faulty or dam-
aged, the expansion valve must be replaced.
OPERATION
High-pressure, high temperature liquid refrigerant
from the liquid line passes through the expansion
valve orifice, converting it inot a low-pressure, low-
temperature mixture of liquid and gas before it
enters the evaporator coil. A temperature sensor in
the expansion valve control head monitors the tem-
perature of the refrigerant leaving the evaporator coil
throught the suction line, and adjusts the orifice size
at the liquid line to let the proper amoount of refrig-
erant into the evaporator coil to meet the vehicle
cooling requirements. Controlling the refrigerant flow
through the evaporator ensures that none of the
refrigerant leaving the evaporator is still in a liquid
state, which could damage the compressor.
DIAGNOSIS AND TESTING - A/C EXPANSION
VALVE
The expansion valve is located on the engine side
of the dash panel near the shock tower.
The expansion valve can fail in three different
positions (open, closed or restricted).
In an Open Position: this will result in a noisy
compressor or no cooling. The cause can be broken
spring, broken ball or excessive moisture in the A/C
system. If the spring or ball are found to be defective,
replace the expansion valve. If excessive moisture is
found in the A/C system, recycle the refrigerant.
In a Closed Position: There will be low suction
pressure and no cooling. This may be caused by a
failed power dome or excessive moisture in the A/C
system. If the power dome on the expansion valve is
found to be defective replace the expansion valve. If
excessive moisture is found recycle the refrigerant.
A Restricted Orifice: There will be low suction
pressure and no cooling. This may be caused by
debris in the refrigerant system. If debris is believed
to be the cause, recycle the refrigerant and replace
the expansion valve and the receiver/drier.
WJPLUMBING 24 - 65
A/C DISCHARGE LINE (Continued)

HEATER CORE
DESCRIPTION
The heater core is located in the HVAC housing,
under the instrument panel. It is a heat exchanger
made of rows of tubes and fins.
OPERATION
Engine coolant is circulated through heater hoses
to the heater core at all times. As the coolant flows
through the heater core, heat removed from the
engine is transferred to the heater core fins and
tubes. Air directed through the heater core picks up
the heat from the heater core fins. The temperature
control door allows control of the heater output air
temperature by controlling how much of the air flow-
ing through the HVAC housing is directed through
the heater core. The blower motor speed controls the
volume of air flowing through the HVAC housing.
The heater core cannot be repaired and, if faulty or
damaged, it must be replaced. Refer to Cooling for
more information on the engine cooling system, the
engine coolant and the heater hoses.
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN AN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
(1) Remove the HVAC housing from the vehicle.
(Refer to 24 - HEATING & AIR CONDITIONING/
DISTRIBUTION/HVAC HOUSING - REMOVAL)
(2) Remove the foam gasket surrounding the core
tubes.
NOTE: Notice the orientation of the irregularly
shaped gasket on the tubes. The gasket must be
placed correctly to ensure proper sealing against
the body during reinstallation.(3)
Remove the screws and retainers that secure the
heater core and tubes to the HVAC housing (Fig. 12).
(4) Remove the mode door actuator if necessary,
for clearance to remove the core.
(5) Lift the heater core straight up and out of the
HVAC housing (Fig. 13).
(6) When replacing individual tubes, loosen and
remove the round tube-to-core clamp, and pull tube
from core.
INSTALLATION
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
Any kinks or sharp bends in the refrigerant plumb-
ing will reduce the capacity of the entire air condi-
tioning system. Kinks and sharp bends reduce the
flow of refrigerant in the system. A good rule for the
flexible hose refrigerant lines is to keep the radius of
all bends at least ten times the diameter of the hose.
In addition, the flexible hose refrigerant lines should
be routed so they are at least 80 millimeters (3
inches) from the exhaust manifold.
High pressures are produced in the refrigerant sys-
tem when the air conditioning compressor is operat-
ing. Extreme care must be exercised to make sure
that each of the refrigerant system connections is
Fig. 12 HEATER CORE, TUBES, AND RETAINERS
1 - TUBE-TO-CORE CLAMPS
2 - GROUND STRAP
3 - HVAC HOUSING
4 - TUBE RETAINERS AND SCREWS
5 - HEATER CORE
WJPLUMBING 24 - 71

pressure-tight and leak free. It is a good practice to
inspect all flexible hose refrigerant lines at least once
a year to make sure they are in good condition and
properly routed.
(1) When installing individual tubes, insert tube
into core ensuring that tube O-ring is seated in core
and not pinched. Hold tube in seated position while
installing the round tube-to-core clamp (Fig. 14).
NOTE: The round tube-to-heater-core clamp should
be left loose enough to turn the tube in the core.
Position the core in the housing, and then tighten
the tube-to-heater-core clamp after orienting the
tubes to the molded HVAC housing.
(2) Lower the heater core into the HVAC housing.
(3) Install the mode door actuator, if removed from
housing for core removal.
(4) Position the retainers over the heater core
tubes. Install and tighten the screws that secure the
heater core and retainers to the HVAC housing.
Tighten the screws to 2.2 N´m (20 in. lbs.).NOTE: The grounding strap is to be attached to the
lower heater core tube retainer.
(5) Reinstall the HVAC housing to the vehicle.
(Refer to 24 - HEATING & AIR CONDITIONING/
DISTRIBUTION/HVAC HOUSING - INSTALLA-
TION)
RECEIVER / DRIER
DESCRIPTION
The receiver/drier is mounted in the engine com-
partment between the condenser and is part of the
liquid line assembly. The filter/drier cannot be
repaired, if the filter/drier is faulty, damaged, left
open to the atmosphere or contaminated the line
assembly must be replaced.
OPERATION
The filter-drier performs a filtering action to pre-
vent foreign material in the refrigerant from contam-
inating the expansion valve. A desiccant bag is
mounted inside the filter-drier canister to absorb any
Fig. 13 HEATER CORE AND TUBES - (Typical)
1 - ELECTRICAL CONNECTORS
2 - EXPANSION VALVE
3 - ELECTRIC ACTUATOR
4 - OUTLET TO DEFROSTER DUCTS
5 - ELECTRIC ACTUATOR
6 - FLOOR DUCT
7 - TO REAR PASSENGER FLOOR AIR DUCTS8 - FLOOR DUCT
9 - HEATER CORE AND TUBES
10 - HOUSING DRAIN
11 - BLOWER MOTOR RESISTOR/CONTROLLER
12 - BLOWER MOTOR
13 - GROUND STRAP
24 - 72 PLUMBINGWJ
HEATER CORE (Continued)

(M)Malfunction Indicator Lamp (MIL) illuminated during engine operation if this DTC was recorded
(depending if required by CARB and/or EPA). MIL is displayed as an engine icon on instrument panel.
(G)Generator lamp illuminated
Generic Scan
Tool P-CodeDRB Scan Tool Display Brief Description of DTC
P0057 (M) 2/2 O2 Sensor Heater Circuit Low Problem detected in oxygen sensor heater relay circuit.
P0058 (M) 2/2 O2 Sensor Heater Circuit High Problem detected in oxygen sensor heater relay circuit.
P0071 (M) Amb/Bat Temp Sensor Performance
P0106 Barometric Pressure Out of Range MAP sensor input voltage out of an acceptable range
detected during reading of barometric pressure at key-on.
P0107 (M) Map Sensor Voltage Too Low MAP sensor input below minimum acceptable voltage.
P0108 (M) Map Sensor Voltage Too High MAP sensor input above maximum acceptable voltage.
PO111 (M) Intake Air Temp Sensor Performance
P0112 (M) Intake Air Temp Sensor Voltage Low Intake air (charge) temperature sensor input below the
minimum acceptable voltage.
P0113 (M) Intake Air Temp Sensor Voltage High Intake air (charge) temperature sensor input above the
maximum acceptable voltage.
P0116 Coolant Temp Sensor Performance A rationatilty error has been detected in the coolant temp
sensor.
P0117 (M) ECT Sensor Voltage Too Low Engine coolant temperature sensor input below the
minimum acceptable voltage.
P0118 (M) ECT Sensor Voltage Too High Engine coolant temperature sensor input above the
maximum acceptable voltage.
P0121 (M) TPS Voltage Does Not Agree With
MAPTPS signal does not correlate to MAP sensor signal.
P0121 (M) Accelerator Position Sensor (APPS)
Signal Voltage Too LowAPPS voltage input below the minimum acceptable
voltage.
P0122 (M) Throttle Position Sensor Voltage Low Throttle position sensor input below the acceptable
voltage range.
P0122 (M) Accelerator Position Sensor (APPS)
Signal Voltage Too LowAPPS voltage input below the minimum acceptable
voltage.
P0123 (M) Throttle Position Sensor Voltage
HighThrottle position sensor input above the maximum
acceptable voltage.
P0123 (M) Accelerator Position Sensor (APPS)
Signal Voltage Too HighAPPS voltage input above the maximum acceptable
voltage.
P0125 (M) Closed Loop Temp Not Reached Time to enter Closed Loop Operation (Fuel Control) is
excessive.
P0125 (M) Engine is Cold Too Long Engine does not reach operating temperature.
P0130 (M) 1/1 O2 Sensor Heater Circuit
MalfunctionOxygen sensor heater element malfunction.
P0131 (M) 1/1 O2 Sensor Shorted To Ground Oxygen sensor input voltage maintained below normal
operating range.
P0132 (M) 1/1 O2 Sensor Shorted To Voltage Oxygen sensor input voltage maintained above normal
operating range.
P0133 (M) 1/1 O2 Sensor Slow Response Oxygen sensor response slower than minimum required
switching frequency.
P0134 (M) 1/1 O2 Sensor Stays at Center Neither rich or lean condition is detected from the oxygen
sensor input.
WJEMISSIONS CONTROL 25 - 3
EMISSIONS CONTROL (Continued)

(M)Malfunction Indicator Lamp (MIL) illuminated during engine operation if this DTC was recorded
(depending if required by CARB and/or EPA). MIL is displayed as an engine icon on instrument panel.
(G)Generator lamp illuminated
Generic Scan
Tool P-CodeDRB Scan Tool Display Brief Description of DTC
P0172 (M) 1/1 Fuel System Rich A rich air/fuel mixture has been indicated by an
abnormally lean correction factor.
P0174 (M) 2/1 Fuel System Lean A lean air/fuel mixture has been indicated by an
abnormally rich correction factor.
P0175 (M) 2/1 Fuel System Rich A rich air/fuel mixture has been indicated by an
abnormally lean correction factor.
P0176 Loss of Flex Fuel Calibration Signal No calibration voltage present from flex fuel sensor.
P0177 Water In Fuel Excess water found in fuel by water-in-fuel sensor.
P0178 Flex Fuel Sensor Volts Too Low Flex fuel sensor input below minimum acceptable voltage.
P0178 Water In Fuel Sensor Voltage Too
LowLoss of water-in-fuel circuit or sensor.
P0179 Flex Fuel Sensor Volts Too High Flex fuel sensor input above maximum acceptable
voltage.
P0181 Fuel Injection Pump Failure Low power, engine derated, or engine stops.
P0182 (M) CNG Temp Sensor Voltage Too Low Compressed natural gas temperature sensor voltage
below acceptable voltage.
P0183 (M) CNG Temp Sensor Voltage Too High Compressed natural gas temperature sensor voltage
above acceptable voltage.
P0201 (M) Injector #1 Control Circuit An open or shorted condition detected in control circuit for
injector #1 or the INJ 1 injector bank.
P0202 (M) Injector #2 Control Circuit An open or shorted condition detected in control circuit for
injector #2 or the INJ 2 injector bank.
P0203 (M) Injector #3 Control Circuit An open or shorted condition detected in control circuit for
injector #3 or the INJ 3 injector bank.
P0204 (M) Injector #4 Control Circuit Injector #4 or INJ 4 injector bank output driver stage does
not respond properly to the control signal.
P0205 (M) Injector #5 Control Circuit Injector #5 output driver stage does not respond properly
to the control signal.
P0206 (M) Injector #6 Control Circuit Injector #6 output driver stage does not respond properly
to the control signal.
P0207 (M) Injector #7 Control Circuit Injector #7 output driver stage does not respond properly
to the control signal.
P0208 (M) Injector #8 Control Circuit Injector #8 output driver stage does not respond properly
to the control signal.
P0209 (M) Injector #9 Control Circuit Injector #9 output driver stage does not respond properly
to the control signal.
P0210 (M) Injector #10 Control Circuit Injector #10 output driver stage does not respond properly
to the control signal.
P0215 Fuel Injection Pump Control Circuit Failure in fuel pump relay control circuit.
P0216 (M) Fuel Injection Pump Timing Failure High fuel supply restriction, low fuel pressure or possible
wrong or incorrectly installed pump keyway.
P0217 Decreased Engine Performance Due
To Engine Overheat ConditionEngine overheating. ECM will derate engine performance.
WJEMISSIONS CONTROL 25 - 5
EMISSIONS CONTROL (Continued)

(M)Malfunction Indicator Lamp (MIL) illuminated during engine operation if this DTC was recorded
(depending if required by CARB and/or EPA). MIL is displayed as an engine icon on instrument panel.
(G)Generator lamp illuminated
Generic Scan
Tool P-CodeDRB Scan Tool Display Brief Description of DTC
P0406 EGR Position Sensor Volts Too High EGR position sensor input above the acceptable voltage
range.
P0412 Secondary Air Solenoid Circuit An open or shorted condition detected in the secondary
air (air switching/aspirator) solenoid control circuit.
P0420 (M) 1/1 Catalytic Converter Efficiency Catalyst 1/1 efficiency below required level.
P0432 (M) 1/2 Catalytic Converter Efficiency Catalyst 2/1 efficiency below required level.
P0441 (M) Evap Purge Flow Monitor Insufficient or excessive vapor flow detected during
evaporative emission system operation.
P0442 (M) Evap Leak Monitor Medium Leak
DetectedA small leak has been detected in the evaporative
system.
P0443 (M) Evap Purge Solenoid Circuit An open or shorted condition detected in the EVAP purge
solenoid control circuit.
P0455 (M) Evap Leak Monitor Large Leak
DetectedA large leak has been detected in the evaporative system.
P0456 (M) Evap Leak Monitor Small Leak
DetectedLeak has been detected in the evaporative system.
P0460 Fuel Level Unit No Change Over
MilesDuring low fuel
P0460 Fuel Level Unit No Change Over
MilesFuel level sending unit voltage does not change for more
than 40 miles.
PO061 Fuel Level Unit No Change Over
Time
P0462 Fuel Level Sending Unit Volts Too
LowFuel level sensor input below acceptable voltage.
P0462 (M) Fuel Level Sending Unit Volts Too
LowOpen circuit between PCM and fuel gauge sending unit.
P0463 Fuel Level Sending Unit Volts Too
HighFuel level sensor input above acceptable voltage.
P0463 (M) Fuel Level Sending Unit Volts Too
HighCircuit shorted to voltage between PCM and fuel gauge
sending unit.
P0500 (M) No Vehicle Speed Sensor Signal No vehicle speed sensor signal detected during road load
conditions.
P0500 (M) No Vehicle Speed Sensor Signal A vehicle speed signal was not detected.
P0505 (M) Idle Air Control Motor Circuits
P0508 (M) IAC Motor Sense Circuit Low
P0509 (M) IAC Motor Sense Circuit High
P0521 Oil Pressure Switch Rationality
P0522 Oil Pressure Voltage Too Low Oil pressure sending unit (sensor) voltage input below the
minimum acceptable voltage.
P0523 Oil Pressure Voltage Too High Oil pressure sending unit (sensor) voltage input above the
maximum acceptable voltage.
P0524 Oil Pressure Too Low Engine oil pressure is low. Engine power derated.
25 - 8 EMISSIONS CONTROLWJ
EMISSIONS CONTROL (Continued)

(M)Malfunction Indicator Lamp (MIL) illuminated during engine operation if this DTC was recorded
(depending if required by CARB and/or EPA). MIL is displayed as an engine icon on instrument panel.
(G)Generator lamp illuminated
Generic Scan
Tool P-CodeDRB Scan Tool Display Brief Description of DTC
P0545 A/C Clutch Relay Circuit Problem detected in air conditioning clutch relay control
circuit.
P0551 Power Steering Switch Failure Incorrect input state detected for the power steering
switch circuit. PL: High pressure seen at high speed.
P0562 Charging System Voltage Too Low Supply voltage sensed at ECM too low.
P0563 Charging System Voltage Too High Supply voltage sensed at ECM too high.
P0572 Brake Switch Input #1 Signal
Missing
P0573 Brake Switch Input #2 Signal
Missing
P0575 Cruise Control Switch Voltage Low
P0576 Cruise Control Switch Voltage High
P0577 Cruise Control Switch Voltage High
P0600 PCM Failure SPI Communications No communication detected between co-processors in the
control module.
P0601 (M) Internal Controller Failure Internal control module fault condition (check sum)
detected.
P0602 (M) ECM Fueling Calibration Error ECM Internal fault condition detected.
P0604 RAM Check Failure Transmission control module RAM self test fault detected.
-Aisin transmission
P0605 ROM Check Falure Transmission control module ROM self test fault detected
-Aisin transmission
P0606 (M) ECM Failure ECM Internal fault condition detected.
P0615 Starter Relay Control Circuit An open or shorted condition detected in the starter relay
control circuit.
P0622 (G) Generator Field Not Switching
ProperlyAn open or shorted condition detected in the generator
field control circuit.
P0645 A/C Clutch Relay Circuit An open or shorted condition detected in the A/C clutch
relay control circuit.
P0700 EATX Controller DTC Present This SBEC III or JTEC DTC indicates that the EATX or
Aisin controller has an active fault and has illuminated the
MIL via a CCD (EATX) or SCI (Aisin) message. The
specific fault must be acquired from the EATX via CCD or
from the Aisin via ISO-9141.
P0703 Brake Switch Stuck Pressed or
ReleasedIncorrect input state detected in the brake switch circuit.
(Changed from P1595)
P0703 Brake Switch Sense Circuit
P0711 (M) Trans Temp Sensor, No Temp Rise
After StartRelationship between the transmission temperature and
overdrive operation and/or TCC operation indicates a
failure of the Transmission Temperature Sensor. OBD II
Rationality. Was MIL code 37.
P0712 Trans Temp Sensor Voltage Too Low Transmission fluid temperature sensor input below
acceptable voltage. Was MIL code 37.
WJEMISSIONS CONTROL 25 - 9
EMISSIONS CONTROL (Continued)