P0031 TOYOTA RAV4 2006 Service Repair Manual

ENGINE - 2GR-FE ENGINEEG-133
15. Fail-safe
When the ECM detects a malfunction, the ECM stops or controls the engine according to the date already
stored in the memory.
Fail-safe Chart
DTC No.Fail-safe OperationFail-safe Deactivation Conditions
P0031, P0032,
P0051, P0052ECM turns off air-fuel ratio sensor heater.Ignition switch OFF.
P0037, P0038,
P0057, P0058ECM turns off heated oxygen sensor heater.Ignition switch OFF.
P0100, P0102,
P0103Ignition timing is calculated from engine speed
and throttle angle.“Pass” condition detected.
P0110, P0112,
P0113Intake air temperature is fixed at 20C (68F).“Pass” condition detected.
P0115, P0117,
P0118Engine coolant temperature is fixed at 80C
(176
F).“Pass” condition detected.
P0120, P0121,
P0122, P0123,
P0220, P0222,
P0223, P0604,
P0606, P0607,
P0657, P2102,
P2103, P2111,
P2112, P2118,
P2119, P2135
If ETCS-i (Electronic Throttle Control
System-intelligent) has a malfunction, ECM
cuts off current to throttle control motor.
Throttle control valve returns to predetermined
opening angle (approximately 6.5
) by force of
return spring. ECM then adjusts engine output
by controlling fuel injection (intermittent
fuel-cut) and ignition timing in accordance with
accelerator pedal opening angel to enable
vehicle to continue driving at minimal speed. If
accelerator pedal is depressed firmly and
slowly, vehicle can be driven slowly. If
accelerator pedal is depressed quickly, vehicle
may speed up and slow down erratically.If “Pass” condition is detected and
then the ignition switch is turned
OFF, fail-safe operation will stop
and system will return to normal
operating conditions.
P0327, P0328,
P0332, P0333Max. timing retardation.Ignition switch OFF.
P0351, P0352,
P0353, P0354,
P0355, P0356
Fuel is cut.“Pass” condition detected.
P2120, P2121,
P2122, P2123,
P2125, P2127,
P2128, P2138
Accelerator pedal position sensor has two (main
and sub) sensor circuits. If a malfunction occurs
in either of sensor circuits, ECM detects
abnormal signal voltage difference between two
sensor circuits and switches into limp mode. In
limp mode, remaining circuit is used to calculate
accelerator pedal opening to allow vehicle to
continue driving. If both circuits malfunction,
ECM regards opening angle of accelerator pedal
to be fully closed. In this case, throttle valve will
remain closed as if engine is idling.
If “Pass” condition is detected and
then the ignition switch is turned
OFF, fail-safe operation will stop
and system will return to normal
operating conditions.

ES–462AZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
FAIL-SAFE CHART
If any of the following DTCs are set, the ECM enters fail-safe
mode to allow the vehicle to be driven temporarily.
HINT:
*: The vehicle can be driven slowly when the accelerator
pedal is depressed firmly and slowly. If the accelerator pedal
is depressed quickly, the vehicle may speed up and slow
down erratically.
DTCs Components Fail-Safe OperationsFail-Safe Deactivation
Conditions
P0031 and P0032Air-Fuel Ratio (A/F) Sensor
HeaterECM turns off A/F sensor heater. Ignition switch OFF
P0037 and P0038Heated Oxygen (HO2) Sensor
HeaterECM turns off HO2 sensor heater. Ignition switch OFF
P0100, P0102 and P0103 Mass Air Flow (MAF) MeterECM calculates ignition timing
according to engine speed and
throttle valve position.Pass condition detected
P0110, P0112 and P0113Intake Air Temperature (IAT)
SensorECM estimates IAT to be 20
C
(68
F).Pass condition detected
P0115, P0117 and P0118Engine Coolant Temperature
(ECT) SensorECM estimates ECT to be 80
C
(176
F).Pass condition detected
P0120, P0121, P0122, P0123,
P0220, P0222, P0223, P0604,
P0606, P0607, P0657, P2102,
P2103, P2111, P2112, P2118,
P2119 and P2135Electronic Throttle Control
System (ETCS)ECM cuts off throttle actuator
current and throttle valve returned
to 6
throttle position by return
spring.
ECM then adjusts engine output
by controlling fuel injection
(intermittent fuel-cut) and ignition
timing in accordance with
accelerator pedal opening angle
to allow vehicle to continue at
minimal speed*.Pass condition detected and then
ignition switch turned OFF
P0327 and P0328 Knock SensorECM sets ignition timing to
maximum retard.Ignition switch OFF
P0351 to P0354 Igniter ECM cuts fuel. Pass condition detected
P1550, P1551, P1552 and P1602 Generator Alternator command is fixed. Pass condition detected
P2120, P2121, P2122, P2123,
P2125, P2127, P2128 and P2138Accelerator Pedal Position (APP)
SensorAPP sensor has 2 sensor circuits:
Main and Sub.
If either circuit malfunctions, ECM
controls engine using other
circuit.
If both circuits malfunction, ECM
regards accelerator pedal as
being released. As result, throttle
valve closed and engine idles.Pass condition detected and then
ignition switch turned OFF

ES–582AZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
DIAGNOSTIC TROUBLE CODE CHART
HINT:
Parameters listed in the chart may be different than your
readings depending on the type of instrument and other
factors.
If any DTCs are displayed during a check mode DTC check,
check the circuit for the DTCs listed in the table below. For
details of each DTC, refer to the page indicated.
DTC No. Detection Item Trouble Areas MIL Memory See page
P0010 Camshaft Position
"A" Actuator Circuit
(Bank 1)- Open or short in Oil
Control Valve (OCV)
circuit
- OCV
- ECMComes on DTC storedES-62
P0011 Camshaft Position
"A" - Timing Over-
Advanced or System
Performance (Bank
1)- Valve timing
- OCV
- OCV filter
- Camshaft timing
gear assembly
- ECMComes on DTC storedES-66
P0012 Camshaft Position
"A" - Timing Over-
Retarded (Bank 1)- Same as DTC
P0011Comes on DTC storedES-66
P0016 Crankshaft Position -
Camshaft Position
Correlation (Bank 1
Sensor A)- Mechanical system
(Timing chain has
jumped tooth or chain
stretched)
- ECMComes on DTC storedES-72
P0031 Oxygen (A/F) Sensor
Heater Control Circuit
Low (Bank 1 Sensor
1)- Open in Air-Fuel
Ratio (A/F) sensor
heater circuit
- A/F sensor heater
(sensor 1)
- Integration relay
(EFI MAIN relay)
- ECMComes on DTC storedES-74
P0032 Oxygen (A/F) Sensor
Heater Control Circuit
High (Bank 1 Sensor
1)- Short in A/F sensor
heater circuit
- A/F sensor heater
(sensor 1)
- Integration relay
(EFI MAIN relay)
- ECMComes on DTC storedES-74
P0037 Oxygen Sensor
Heater Control Circuit
Low (Bank 1 Sensor
2)- Open in Heated
Oxygen (HO2)
sensor heater circuit
- HO2 sensor heater
(sensor 2)
- Integration relay
(EFI MAIN relay)
- ECMComes on DTC storedES-80
P0038 Oxygen Sensor
Heater Control Circuit
High (Bank 1 Sensor
2)- Short in HO2 sensor
heater circuit
- HO2 sensor heater
(sensor 2)
- Integration relay
(EFI MAIN relay)
- ECMComes on DTC storedES-80

2AZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEMES–81
ES
HINT:
• Although the DTC titles say oxygen sensor, these DTCs relate to the Air-Fuel Ratio (A/F) sensor.
• Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and
located near the engine assembly.
DESCRIPTION
Refer to DTC P2195 (see page ES-292).
HINT:
• When either of these DTCs is set, the ECM enters fail-safe mode. The ECM turns off the A/F sensor
heater in fail-safe mode. Fail-safe mode continues until the ignition switch is turned OFF.
• The ECM provides a pulse width modulated control circuit to adjust the current through the heater. The
A/F sensor heater circuit uses a relay on the B+ side of the circuit.
DTC P0031Oxygen (A/F) Sensor Heater Control Circuit
Low (Bank 1 Sensor 1)
DTC P0032Oxygen (A/F) Sensor Heater Control Circuit
High (Bank 1 Sensor 1)
DTC No. DTC Detection Conditions Trouble Areas
P0031Air-Fuel Ratio (A/F) sensor heater current less than 0.8 A
(1 trip detection logic)• Open in A/F sensor heater circuit
• A/F sensor heater (sensor 1)
• Integration relay (EFI MAIN relay)
•ECM
P0032Air-Fuel Ratio (A/F) sensor heater current more than 10 A
(1 trip detection logic)• Short in A/F sensor heater circuit
• A/F sensor heater (sensor 1)
• Integration relay (EFI MAIN relay)
•ECM
A127244E01

ES–822AZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
MONITOR DESCRIPTION
The ECM uses information from the Air-Fuel Ratio (A/F) sensor to regulate the air-fuel ratio and keep it
close to the stoichiometric level. This maximizes the ability of the Three-Way Catalytic Converter (TWC) to
purify the exhaust gases.
The A/F sensor detects oxygen levels in the exhaust gas and transmits the information to the ECM. The
inner surface of the sensor element is exposed to the outside air. The outer surface of the sensor element
is exposed to the exhaust gas. The sensor element is made of platinum coated zirconia and includes an
integrated heating element.
The zirconia element generates a small voltage when there is a large difference in the oxygen
concentrations between the exhaust gas and outside air. The platinum coating amplifies this voltage
generation.
The A/F sensor is more efficient when heated. When the exhaust gas temperature is low, the sensor
cannot generate useful voltage signals without supplementary heating. The ECM regulates the
supplementary heating using a duty-cycle approach to adjust the average current in the sensor heater
element. If the heater current is outside the normal range, the signal transmitted by the A/F sensor
becomes inaccurate, as a result, the ECM is unable to regulate air-fuel ratio properly.
When the current in the A/F sensor heater is outside the normal operating range, the ECM interprets this
as a malfunction in the sensor heater and sets a DTC.
Example:
The ECM sets DTC P0032 when the current in the A/F sensor heater is more than 10 A. Conversely,
when the heater current is less than 0.8 A, DTC P0031 is set.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
All:
P0031:
P0032:
TYPICAL MALFUNCTION THRESHOLDS
P0031:
P0032:
Related DTCsP0031: A/F sensor heater open/short (Low electrical current)
P0032: A/F sensor heater open/short (High electrical current)
Required Sensors/Components (Main) A/F sensor heater
Required Sensors/Components (Related) -
Frequency of Operation Continuous
Duration 10 seconds
MIL Operation Immediate
Sequence of Operation None
Monitor runs whenever following DTCs not present None
Battery voltage 10.5 V or more
A/F sensor heater duty-cycle ratio 50 % or more
Time after engine start 10 seconds or more
Time after engine start 10 seconds or more
A/F sensor heater current Less than 0.8 A
A/F sensor heater current More than 10 A

ES–862AZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
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(a) Disconnect the B7 A/F sensor connector.
(b) Disconnect the B30 ECM connector.
(c) Measure the resistance.
Standard resistance (Check for open)
Standard resistance (Check for short)
(d) Reconnect the A/F sensor connector.
(e) Reconnect the ECM connector.
NG
OK
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch ON.
(c) Turn the tester ON.
(d) Clear DTCs (see page ES-35).
(e) Start the engine.
(f) Allow the engine to idle for 1 minute or more.
(g) Select the following menu items: DIAGNOSIS /
ENHANCED OBD II / DTC INFO / CURRENT CODES.
(h) Read DTCs.
Result
B
A
5CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM)
A127715E01
Tester Connections Specified Conditions
B7-1 (HA1A) - B30-109 (HA1A) Below 1
Tester Connections Specified Conditions
B7-1 (HA1A) or B30-109 (HA1A) -
Body ground10 k
or higher
REPAIR OR REPLACE HARNESS OR
CONNECTOR
6CHECK WHETHER DTC OUTPUT RECURS
Display (DTC Output) Proceed To
No output A
P0031 or P0032 B
REPLACE ECM
CHECK FOR INTERMITTENT PROBLEMS