ECU DAEWOO MATIZ 2003 Service Owner's Manual
[x] Cancel search | Manufacturer: DAEWOO, Model Year: 2003, Model line: MATIZ, Model: DAEWOO MATIZ 2003Pages: 1184, PDF Size: 36 MB
Page 182 of 1184
1F–84 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F130
DIAGNOSTIC TROUBLE CODE (DTC) – P0131 OXYGEN SENSOR LOW
V O LTA G E
Circuit Description
The engine control module (ECM) supplies a voltage of
about 450m volts between the ECM terminals 44 and
13. The oxygen (O
2) sensor varies the voltage within a
range of about 1volt if the exhaust is rich, down to about
100mm volts if the exhaust is lean. The O
2 sensor is like
an open circuit and produces no voltage when it is below
350°C(600°F). An open O
2 sensor circuit or a cold O2
sensor causes “open loop” operation.
Conditions for Setting the DTC
(Case A)
The engine controls system is in closed loop.
Engine speed is less than 6,000rpm.
The oxygen sensor voltage is below 0.07V for at least
40seconds.
DTCs P0107, P0108, P0117, P0118, P0122, P0123,
P0335, P0336, P0341, P0342, P0400, P0404,
P0405, P0406, P0445, P0444 are NOT SET.
(Case B)
The engine controls system is in closed loop.
Engine speed is less than 6,000rpm.
The oxygen sensor voltage is between 0.352 and
0.499 at least 10seconds.
Action Taken when the DTC Sets
The Malfunction Indicator Lamp (MIL) will illuminate.The ECM will record operating conditions at the time
the diagnostic fails. This information will be stored in
the Freeze Frame and Failure Records buffers.
A history DTC is stored.
Conditions for Clearing the MIL/DTC
The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm-up
cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Disconnecting the ECM battery feed for more than 10
seconds.
Diagnostic Aids
Normal scan tool voltage varies between 0.1volts and
0.9 volts while in closed loop.
Inspect the oxygen (O
2) sensor wire. The O2 sensor
may be positioned incorrectly and contacting the ex-
haust manifold.
Check for an intermittent ground in the wire between the
O
2 sensor and the engine control module.
Perform an injector 2alance test to determine if a re-
stricted fuel injector may be causing the lean condition.
Vacuum of crankcase leaks will cause a lean running
condition.
An exhaust manifold gasket leak of a cracked exhaust
manifold may cause outside air to be pulled into the ex-
haust and past the sensor.
Page 186 of 1184
1F–88 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F130
DIAGNOSTIC TROUBLE CODE (DTC) – P0132 OXYGEN SENSOR HIGH
V O LTA G E
Circuit Description
The engine control module (ECM) supplies a voltage of
about 450mm volts between the ECM terminals 44 and
13. The oxygen (O2) sensor varies the voltage within a
range of about 1volt if the exhaust is rich, down to about
100mm volts if the exhaust is lean. The O
2 sensor is like
an open circuit and produces no voltage when it is below
350°C(600°F). An open O
2 sensor circuit or a cold O2
sensor causes “open loop” operation.
Conditions for Setting the DTC
The oxygen sensor voltage is more than 4.8V for at
least 0.2 seconds.
A high voltage condition exists.
Action Taken when the DTC Sets
The Malfunction Indicator Lamp (MIL) will illuminate.
The ECM will record operating conditions at the time
the diagnostic fails. This information will be stored in
the Freeze Frame and Records buffers.
A history DTC is stored.
Conditions for Clearing the MIL/DTC
The MIL will turn off after consecutive ignition cycles
in which the diagnostic runs without a fault.A history DTC will clear after 40 consecutive warm up
cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Disconnecting the ECM battery feed for 10 seconds.
Diagnostic Aids
Normal scan tool voltage varies between 0.1volts and
0.9volts while in closed loop.
Inspect the oxygen (O2) sensor wire. The O2 sensor
may be positioned incorrectly and contacting the ex-
haust manifold.
Check for an intermittent ground in the wire between the
O
2 sensor and the engine control module.
Perform an injector 2alance test to determine if a re-
stricted fuel injector may be causing the lean condition.
Vacuum of crankcase leaks will cause a lean running
condition.
An exhaust manifold gasket leak of a cracked exhaust
manifold may cause outside air to be pulled into the ex-
haust and past the sensor.
Page 188 of 1184
1F–90 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F130
DIAGNOSTIC TROUBLE CODE (DTC) – P0133 OXYGEN SENSOR NO ACTIVITY
Circuit Description
The engine control module (ECM) supplies a voltage of
about 450mm volts between the ECM terminals 44 and
13. The oxygen (O
2) sensor varies the voltage within a
range of about 1volt if the exhaust is rich, down to about
100mm volts if the exhaust is lean. The O
2 sensor is like
an open circuit and produces no voltage when it is below
360°C(600°F). An open O
2 sensor circuit or a cold O2
sensor causes “open loop” operation.
Conditions for Setting the DTC
The engine controls system is in closed loop.
Engine Coolant Temperature is higher than 60°C
(140°F).
The mass air flow(MAF) is between 75mg/tdc and
100mg/tdc.
The engine speed is between 3,008rpm and
3,500rpm.
The vehicle speed is between 45km/h(27.96mph)
and 55km/h(34.2mph).
The manifold air pressure is higher than 90kPa.
The ignition is at 10 volts.
The upstream O
2 sensor periods higher than 1.6 sec-
onds.
A number of glitches higher than 5 during the test.DTCs P0107, P0108, P0112, P0113, P0117, P0118,
P0122, P0123, P0131, P0132, P0131, P0132,
P0137, P0138, P1671, P0300, P0335, P0336,
P0341, P0400, P0404, P0405, P0444, P0445 are
NOT SET.
Action Taken when the DTC Sets
Emission related.
“Armed” after two trip with a fail.
“Disarmed” after one trip with a pass.
MIL on if failure is detected in three consecutive trips.
Stores a History DTC on the third consecutive with a
fail (The DTC will be armed after the second fail).
Stores a Freeze Frame on the third consecutive trip
with a fail (if empty).
Conditions for Clearing the MIL/DTC
The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm up
cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Diagnostic Aids
Normal scan tool voltage varies between 0.15 to 8.5mV
while in Closed Loop. If DTC P0133 is intermittent, refer
to “Intermittent” in this Section.
Page 192 of 1184
1F–94 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F140
DIAGNOSTIC TROUBLE CODE (DTC) – P0137 HEATED OXYGEN SENSOR LOW
V O LTA G E
Circuit Description
The engine control module (ECM) supplies a voltage of
about 450mm volts between the ECM terminals 44 and
13. The oxygen (O
2) sensor varies the voltage within a
range of about 1volt if the exhaust is rich, down to about
100mm volts if the exhaust is lean. The O
2 sensor is like
an open circuit and produces no voltage when it is below
360°C(600°F). An open O
2 sensor circuit or a cold O2
sensor causes “open loop” operation.
Conditions for Setting the DTC
(Case A)
The engine controls system is in closed loop.
Engine speed is less than 6,000rpm.
The heated oxygen sensor voltage is below 0.07V for
at least 40 seconds.
DTCs P0107, P0108, P0117, P0118, P0122, P0123,
P0335, P0336, P0341, P0342, P0400, P0404,
P0405, P0406 are NOT SET.
(Case B)
The engine controls system is in closed loop.
Engine speed is less than 6,000rpm.
The heated oxygen sensor voltage is between 0.352
and 0.499 at least 60 seconds.
Action Taken when the DTC Sets
Emission related.
“Armed” after two trip with a fail.
“Disarmed” after one trip with a pass.MIL on if failure is detected in three consecutive trips.
Stores a History DTC on the third consecutive with a
fail (The DTC will be armed after the second fail).
Stores a Freeze Frame on the third consecutive trip
with a fail (if empty).
Conditions for Clearing the MIL/DTC
The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm up
cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Diagnostic Aids
Normal scan tool voltage varies between 0.1 volts
and 0.9 volts while in closed loop.
Inspect the oxygen (O
2) sensor wire. The O2 sensor
may be positioned incorrectly and contacting the ex-
haust manifold.
Check for an intermittent ground in the wire between
the O
2 sensor and the engine control module.
Perform an injector balance test to determine if a re-
stricted fuel injector may be causing the lean condi-
tion.
Vacuum of crankcase leaks will cause a lean running
condition.
An exhaust manifold gasket leak of a cracked ex-
haust manifold may cause outside air to be pulled into
the exhaust and past the sensor.
Page 196 of 1184
1F–98 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F140
DIAGNOSTIC TROUBLE CODE (DTC) – P0138 HEATED OXYGEN SENSOR HIGH
V O LTA G E
Circuit Description
The engine control module (ECM) supplies a voltage of
about 450mm volts between the ECM terminals 64 and
13. The Heated oxygen (O
2) sensor varies the voltage
within a range of about 1volt if the exhaust is rich, down
to about 100mm volts if the exhaust is lean. The Heated
O
2 sensor is like an open circuit and produces no volt-
age when it is below 360°C(600°F). An open O
2 sensor
circuit or a cold O
2 sensor causes “open loop” operation.
Conditions for Setting the DTC
The Heated oxygen sensor voltage is more than 4.8V
for at least 0.2 seconds.
A high voltage condition exists.
Action Taken when the DTC Sets
Emission related.
“Armed” after two trip with a fail.
“Disarmed” after one trip with a pass.
MIL on if failure is detected in three consecutive trips.
Stores a History DTC on the third consecutive with a
fail (The DTC will be armed after the second fail).
Stores a Freeze Frame on the third consecutive trip
with a fail (if empty).Conditions for Clearing the MIL/DTC
The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm up
cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Diagnostic Aids
Normal scan tool voltage varies between 0.1volts and
0.9volts while in closed loop.
Inspect the oxygen (O
2) sensor wire. The O2 sensor
may be positioned incorrectly and contacting the ex-
haust manifold.
Check for an intermittent ground in the wire between
the O
2 sensor and the engine control module.
Perform an injector 2alance test to determine if a re-
stricted fuel injector may be causing the lean condi-
tion.
Vacuum of crankcase leaks will cause a lean running
condition.
An exhaust manifold gasket leak of a cracked ex-
haust manifold may cause outside air to be pulled into
the exhaust and past the sensor.
Page 198 of 1184
1F–100 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F140
DIAGNOSTIC TROUBLE CODE (DTC) – P0140 HEATED OXYGEN SENSOR NO
ACTIVITY
Circuit Description
The engine control module (ECM) supplies a voltage of
about 450mm volts between the ECM terminals 64 and
13. The oxygen (O
2) sensor varies the voltage within a
range of about 1volt if the exhaust is rich, down to about
100mm volts if the exhaust is lean. The O
2 sensor is like
an open circuit and produces no voltage when it is below
360°C(600°F). An open O
2 sensor circuit or a cold O2
sensor causes “open loop” operation.
Conditions for Setting the DTC
The engine controls system is in closed loop.
Engine Coolant Temperature is higher than 70°C
(140°F).
The mass air flow(MAF) is between 25kg/h and
50kg/h.
The engine speed is between 2,400rpm and 300rpm.
The vehicle speed is between 64km/h(12.4mph) and
80km/h(24.9mph).
The manifold air pressure is higher than 70kPa.
The ignition is at 10 volts.
No transition from rich side to lean side or lean side to
rich side during 7.8 seconds even with a forcing of O
2
sensor controller.
DTCs P0107, P0108, P0112, P0113, P0117, P0118,
P0122, P0123, P0137, P0138, P0137, P0138,P0137, P0138, P1671, P0300, P0335, P0336,
P0341, P0400, P0404, P0405, P0644, P0645 are
NOT SET.
Action Taken when the DTC Sets
Emission related.
“Armed” after two trip with a fail.
“Disarmed” after one trip with a pass.
MIL on if failure is detected in three consecutive trips.
Stores a History DTC on the third consecutive with a
fail (The DTC will be armed after the second fail).
Stores a Freeze Frame on the third consecutive trip
with a fail (if empty).
Conditions for Clearing the MIL/DTC
The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm up
cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Disconnecting the ECM battery feed for 10 seconds.
Diagnostic Aids
Normal scan tool voltage varies between 0.15 to
8.5mV while in Closed Loop. If DTC P0140 is inter-
mittent, refer to “Intermittent” in this Section.
Page 202 of 1184
1F–104 ENGINE CONTROLS
DAEWOO M-150 BL2
MAA1F140
DIAGNOSTIC TROUBLE CODE (DTC) – P0141 HEATED OXYGEN SENSOR
HEATER MALFUNCTION
Circuit Description
The engine control module (ECM) supplies a voltage of
about 450mm volts between the ECM terminals 44 and
13. The oxygen (O
2) sensor varies the voltage within a
range of about 1volt if the exhaust is rich, down to about
100mm volts if the exhaust is lean. The O
2 sensor is like
an open circuit and produces no voltage when it is below
360°C(600°F). An open O
2 sensor circuit or a cold O2
sensor causes “open loop” operation.
Conditions for Setting the DTC
Heated oxygen sensor 5V reference voltage supply
circuit high voltage or ground.
Heated oxygen sensor 5V reference voltage supply
circuit open.
Action Taken when the DTC Sets
Emission related.
“Armed” after two trip with a fail.
“Disarmed” after one trip with a pass.
MIL on if failure is detected in three consecutive trips.
Stores a History DTC on the third consecutive with a
fail (The DTC will be armed after the second fail).
Stores a Freeze Frame on the third consecutive trip
with a fail (if empty).Conditions for Clearing the MIL/DTC
The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm up
cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Diagnostic Aids
Normal scan tool voltage varies between 0.1volts and
0.9 volts while in closed loop.
Inspect the oxygen (O
2) sensor wire. The O2 sensor
may be positioned incorrectly and contacting the ex-
haust manifold.
Check for an intermittent ground in the wire between
the O
2 sensor and the engine control module.
Perform an injector 2alance test to determine if a re-
stricted fuel injector may be causing the lean condi-
tion.
Vacuum of crankcase leaks will cause a lean running
condition.
An exhaust manifold gasket leak of a cracked ex-
haust manifold may cause outside air to be pulled into
the exhaust and past the sensor.
Page 204 of 1184
1F–106 ENGINE CONTROLS
DAEWOO M-150 BL2
DIAGNOSTIC TROUBLE CODE (DTC) – P0171 FUEL TRIM SYSTEM TOO LEAN
System Description
To provide the best possible combination of driveability,
fuel economy, and emission control, a Closed Loop air/
fuel metering system is used. While in Closed Loop, the
Engine Control Module (ECM) monitors the oxygen sen-
sor (O2S) signal voltage and adjusts fuel delivery based
on signal voltage. A change made to fuel delivery will be
indicated by the long and short term fuel trim values
which can be monitored with the scan tool. Ideal fuel trim
values are around 128 (0%). If the O2S signal is indicat-
ing a lean condition, the ECM will add fuel resulting in
fuel trim values above 128 (0% to 100%). If a rich condi-
tion is detected, the fuel trim values will be below 128
(0% to –100%), indicating that the ECM is reducing the
amount of fuel delivered. If exhaust emissions reach an
excessive level due to a lean or rich condition, a fuel trim
Diagnostic Trouble Code (DTC) is set.
Conditions for Setting the DTC
No intrusive tests active.
DTCs P0106, P0107, P0108, P0112, P0113, P0117,
P0118, P0122, P0123, P0125, P0131, P0132,
P0133, P0134, P0137, P0138, P0140, P0141,
P1167, P1171, P0201, P0202, P0203, P0204,
P0300, P0336, P0337, P0341, P0342, P0402,
P0404, P1404, P0405, P0406, P0443, P0506, and
P0507are not set.
The average of short term fuel trim value is greater
than or equal to 120.
Throttle Position (TP) is less than 95%.
Engine speed is between 700 and 6000 rpm.
Barometric Pressure (BARO) is greater than 92.0
kPa (10.4 psi).
Coolant temperature is between 80°C (176°F) and
11 5°C (239°F).
Manifold Absolute Pressure (MAP) is more than 90
kPa (10.2 psi).
System is in closed loop.
Adaptive index is ready.
Action Taken when the DTC Sets
Emission related.
“Armed” after two trip with a fail.
“Disarmed” after one trip with a pass.
MIL on if failure is detected in three consecutive trips.
Stores a History DTC on the third consecutive with a
fail (The DTC will be armed after the second fail).Stores a Freeze Frame on the third consecutive trip
with a fail (if empty).
Conditions for Clearing the MIL/DTC
The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm up
cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Diagnostic Aids
Important: After repairs, use the scan tool Fuel Trim
Reset function to reset the long-term fuel trim to 128
(0%).
Fuel pressure – The system will be lean if the pres-
sure is too low. It may be necessary to monitor fuel
pressure while driving the vehicle at various road
speeds and/or loads to confirm.
Map sensor – An output that causes the ECM to
sense a lower than normal manifold pressure (high
vacuum) can cause the system to go lean. Discon-
necting the MAP sensor will allow the ECM to substi-
tute a fixed (default) value for the MAP sensor. If the
lean condition is gone when the sensor is discon-
nected, substitute a known good sensor and recheck.
Fuel contamination – Water, in even small amounts,
near the in-tank fuel pump inlet can be delivered to
the injector. The water causes a lean exhaust and
can set DTC P0171.
Check for poor O2S or MAP sensor connection at the
ECM. Inspect the harness connectors for the following
conditions:
Backed-out terminals
Improper mating
Broken locks
Improperly formed
Damaged terminals
Poor terminal-to-wire connection
Inspect the wiring harness for damage. If the harness
appears to be OK, observe the O2S display on the scan
tool while moving the connectors and the wiring harness
related to the engine harness. A change in the display
will indicate the location of the fault.
Check the brake power booster check valve for possible
leaks.
Page 205 of 1184
ENGINE CONTROLS 1F–107
DAEWOO M-150 BL2
DTC P0171 – Fuel Trim System Too Lean
StepActionValue(s)YesNo
1
Perform an Euro On-Board Diagnostic (EOBD)
System Check.
Is the system check complete?
–
Go to Step 2
Go to
“On-Board
Diagnostic
System Check”
2
1. Install the scan tool to the Data Link Connector
(DLC).
2. Turn the ignition ON.
Are any component related Diagnostic Trouble
Codes (DTCs) set?
–Go to
Applicable DTC
table
Go to Step 3
3
With the engine running, operate the vehicle until the
LOOP STATUS indicates closed.
Is the Long Term Fuel Trim value below the
specified value?
–22%Go to Step 4Go to Step 5
4
1. Turn the ignition switch ON, with the engine OFF.
2. Review the Freeze Frame data and note the
parameters.
3. Operate the vehicle within the Freeze Frame
conditions and Conditions for Setting The DTC as
noted.
Does the Long Term Fuel Trim value go below the
specified value while operating under the specified
conditions?
–22%Go to Step 16Go to Step 5
5
Visually/physically check the following items:
Vacuum hoses for splits, kinks and improper
connections.
Crankcase ventilation oil/air separator for proper
installation.
Exhaust system for corrosion, leaks, loose or
missing hardware.
Oxygen sensor (O2S) is installed securely and
the pigtail harness is not contacting exhaust
manifold or engine.
Fuel for excessive water, alcohol, or other
contaminants.
Engine Control Module (ECM) and sensor
grounds are clean, tight, and in their proper
locations.
Do any of the above checks isolate a condition
requiring repair?
–
Go to Step 7Go to Step 6
6
1. Disconnect the Manifold Absolute Pressure
(MAP) sensor electrical connector.
2. Operate the vehicle in Closed Loop while
monitoring the Long Term Fuel Trim value.
Is the Long Term Fuel Trim value below the
specified value?
–22%Go to Step 15Go to Step 9
7
1. Repair the malfunction found in Step 5.
2. Recheck the Long Term Fuel Trim value while
operating the engine.
Is the Long Term Fuel Trim value below the
specified value?
–22%Go to Step 8Go to Step 9
8
Lean condition is not present.
Does a driveability problem exist?
–
Go to
“Symptom
Diagnosis”
Go to Step 16
Page 207 of 1184
ENGINE CONTROLS 1F–109
DAEWOO M-150 BL2
DIAGNOSTIC TROUBLE CODE (DTC) – P0172 FUEL TRIM SYSTEM TOO RICH
System Description
To provide the best possible combination of driveability,
fuel economy, and emission control, a Closed Loop air/
fuel metering system is used. While in Closed Loop, the
Engine Control Module (ECM) monitors the oxygen sen-
sor (O2S) signal voltage and adjusts fuel delivery based
on signal voltage. A change made to fuel delivery will be
indicated by the long and short term fuel trim values
which can be monitored with the scan tool. Ideal fuel trim
values are around 128 (0%). If the O2S signal is indicat-
ing a lean condition, the ECM will add fuel resulting in
fuel trim values above 128 (0% to 100%). If a rich condi-
tion is detected, the fuel trim values will be below 128
(0% to –100%), indicating that the ECM is reducing the
amount of fuel delivered. If exhaust emissions reach an
excessive level due to a lean or rich condition, a fuel trim
Diagnostic Trouble Code (DTC) is set.
Conditions for Setting the DTC
No intrusive tests active.
DTCs P0106, P0107, P0108, P0112, P0113, P0117,
P0118, P0122, P0123, P0131, P0132, P0133,
P0134, P0137, P0138, P1167, P1171, P0300,
P0336, P0337, P0341, P0342, P0402, P0404,
P1404, P0405, P0406, P0443, P0506, and P0507are
not set.
The average of short term fuel trim value is greater
than or equal to 120.
Throttle Position (TP) is less than 95%.
Engine speed is between 700 and 6000 rpm.
Barometric Pressure (BARO) is greater than 90.0
kPa (10.4 psi).
Coolant temperature is between 80°C (176°F) and
11 5°C (239°F).
Manifold Absolute Pressure (MAP) is more than 70
kPa (10.2 psi).
System is in closed loop.
Adaptive index is ready.
Action Taken when the DTC Sets
Emission related.“Armed” after two trip with a fail.
“Disarmed” after one trip with a pass.
MIL on if failure is detected in three consecutive trips.
Stores a History DTC on the third consecutive with a
fail (The DTC will be armed after the second fail).
Stores a Freeze Frame on the third consecutive trip
with a fail (if empty).
Conditions for Clearing the MIL/DTC
The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm up
cycles without a fault.
DTC(s) can be cleared by using the scan tool.
Diagnostic Aids
Important: After repairs, use the scan tool Fuel Trim
Reset function to reset the long-term fuel trim to 128
(0%).
Check for poor connection at the ECM. Inspect the har-
ness connectors for the following conditions:
Backed-out terminals.
Improper mating.
Broken locks.
Improperly formed.
Damaged terminals.
Poor terminal-to-wire connection.
Inspect the wiring harness for damage. If the harness
appears to be OK, observe the O2S display on the scan
tool while moving the connectors and the wiring harness
related to the engine harness. A change in the display
will indicate the location of the fault.
If a DTC P1404 is also set, check the 5 volt reference
circuits for a short to voltage.
Check for a restricted exhaust system.
A shorted 5 volt reference circuit may cause a DTC
P0172 to set. Check the 5 volt reference sensors for ab-
normal readings.