o2 sensor TOYOTA HIGHLANDER 2001 Service Repair Manual

A71007
MAF Meter Crankshaft Position Sensor
Actual Valve TimingCorrection Target Valve Timing
Feedback
Duty Control ECM
OCV
Vehicle Speed SignalECT Sensor Throttle Position Sensor
Camshaft Position Sensor
- DIAGNOSTICSSFI SYSTEM (2AZ-FE)
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2005 HIGHLANDER REPAIR MANUAL (RM1144U)
DTC P0010 CAMSHAFT POSITION ºAº ACTUATOR
CIRCUIT (BANK 1)
CIRCUIT DESCRIPTION
The Variable Valve Timing (VVT) system includes the ECM, the Oil Control Valve (OCV) and the VVT control-
ler. The ECM sends a target duty-cycle control signal to the OCV. This control signal, sent to the OCV, regu-
lates the oil pressure applied to the VVT controller. Camshaft timing control is performed based on engine
operation conditions such as intake air volume, throttle position and engine coolant temperature.
The ECM controls the OCV based on the signals output from several sensors. The VVT controller regulates
the intake camshaft angle using oil pressure through the OCV. As a result, the relative position between the
camshaft and the crankshaft is optimized. Also, the engine torque and fuel economy improve, and exhaust
emissions decrease. The ECM detects the actual valve timing using signals from the camshaft position sen-
sor and the crankshaft position sensor. The ECM performs feedback control and verifies target valve timing.
DTC No.DTC Detection ConditionTrouble Area
P0010Open or short in OCV circuit

Open or short in OCV circuit

OCV

ECM
05EST-05

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MONITOR DESCRIPTION
After the ECM sends the ºtargetº duty-cycle signal to the OCV, the ECM monitors the OCV current to estab-
lish an ºactualº duty-cycle. When the actual duty-cycle ratio varies from the target duty-cycle ratio, the ECM
sets a DTC.
MONITOR STRATEGY
Related DTCsP0010: VVT OCV range check
Required sensors / components (Main)VVT OCV
Required sensors / components (Related)-
Frequency of operationContinuous
Duration1 sec.
MIL operationImmediate
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
The monitor will run whenever this DTC is not presentSee page 05-16
Battery voltage11 V or more
Target duty ratio for the OCV70 % or less
StarterOFF
Current cut status for the OCVNot cut
TYPICAL MALFUNCTION THRESHOLDS
Either of the following condition is met:
OCV duty ratio100 % (always ON) despite the target duty ratio is less than 70 %
OCV duty ratio when ECM supplies current to OCV3 % or less despite the ECM is supplying current to the OCV
COMPONENT OPERATING RANGE
VVT OCV duty ratioMore than 3 % and less than 100 %

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DTC P0011 CAMSHAFT POSITION ºAº -TIMING OVER-
ADVANCED OR SYSTEM PERFORMANCE
(BANK 1)
DTC P0012 CAMSHAFT POSITION ºAº -TIMING OVER-
RETARDED (BANK 1)
CIRCUIT DESCRIPTION
Refer to DTC P0010 on page 05-55.
DTC No.DTC Detection ConditionTrouble Area
P0011
After engine is warmed up and engine speed is at 550 to 4,000
rpm, condition (a) continues (1 trip detection logic)
(a) Valve timing does not change from current valve timing
(Problem of advanced valve timing)
Valve timing

OCV

VVT controller assembly

ECM
P0012
After engine is warmed up and engine speed is at 550 to 4,000
rpm, condition (a) continues (2 trip detection logic)
(a) Valve timing does not change from current valve timing
(Problem of retarded valve timing)

Same as DTC No. P0011
MONITOR DESCRIPTION
The ECM optimizes the valve timing using the Variable Valve Timing (VVT) system to control the intake valve
camshaft. The VVT system includes the ECM, the Oil Control Valve (OCV) and the VVT controller. The ECM
sends a target duty-cycle control signal to the OCV. This control signal, sent to the OCV, regulates the oil
pressure applied to the VVT controller. The VVT controller can advance or retard the intake valve camshaft.
Example:
A DTC will be set if: 1) the difference between the ºtargetº and ºactualº valve timing is more than 5 degrees
of the camshaft angle (CA) and the condition continues for more than 4.5 seconds; or 2) the OCV is forcibly
activated 63 times or more.
Advanced cam DTCs are subject to º1 tripº detection logic.
Retarded cam DTCs are subject to º2 tripº detection logic.
MONITOR STRATEGY
Related DTCsP0011: Advanced camshaft timing
P0012: Retarded camshaft timing
Required sensors / components (Main)VVT OCV and VVT Actuators
Required sensors / components (Related)CKP, CMP and ECT sensors
Frequency of operationOnce per driving cycle
DurationWithin 10 sec.
MIL operationP0011: Immediate
P0012: 2 driving cycles
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
The monitor will run whenever these DTCs are not presentSee page 05-16
Battery voltage11 V or more
Throttle position learningCompleted
Engine RPM550 to 4,000 rpm
ECT75 to 100C (167 to 212F)
05ESU-05

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DTC P0016 CRANKSHAFT POSITION - CAMSHAFT
POSITION CORRELATION (BANK 1 SENSOR
A)
CIRCUIT DESCRIPTION
Refer to DTC P0335 and P0339 on page 05-166.
DTC No.DTC Detection ConditionTrouble Area
P0016Deviation in crankshaft position sensor signal and VVT sensor
(bank 1) signal (2 trip detection logic)
Mechanical system (jumped tooth of timing chain, chain
stretched)

ECM
MONITOR DESCRIPTION
The ECM optimizes the valve timing using the Variable Valve Timing (VVT) system to control the intake valve
camshaft. The VVT system includes the ECM, the Oil Control Valve (OCV) and the VVT controller. The ECM
sends a target duty-cycle control signal to the OCV. This control signal, sent to the OCV, regulates the oil
pressure applied to the VVT controller. The VVT controller can advance or retard the intake valve camshaft.
The ECM calibrates the valve timing of the VVT system by setting the camshaft to the maximum retard angle
when the engine is idling. The ECM closes the OCV to retard the cam. The ECM stores this value as a VVT
learning value. When the difference between the target valve timing and the actual valve timing is 5 degrees
or less, the ECM stores this in its memory.
If the learning value meets both of the following conditions (ºaº and ºbº), the ECM interprets this as a defect
in the VVT system and sets a DTC.
(a) The VVT learning value is less than 27CA or more than 49CA.
(b) The Above condition continues for more than 18 seconds.
MONITOR STRATEGY
Related DTCsP0016: Camshaft timing misalignment at Idling
Required sensors / components (Main)VVT actuator
Required sensors / components (Related)CMP and CKP sensors
Frequency of operationOnce per driving cycle
DurationWithin 60 sec.
MIL operation2 driving cycles
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
The monitor will run whenever this DTC is not presentSee page 05-16
Engine RPM550 to 1,400 rpm
TYPICAL MALFUNCTION THRESHOLDS
Duration that either of the following conditions 1 or 2 is met18 sec. or more
1. VVT angle when camshaft is retarded maximumLess than 27CA
2. VVT angle when camshaft is retarded maximumMore than 49CA
0520A-16

A90346
Reference
A/F Sensor
Heater
Sensor
A1A+ HA1A
Duty
Control ECM
From
Battery
EFI NO. 1
Fuse
A1A-
MREL EFI Relay
+B
AF-
AF+ HT
EFI NO. 2
Fuse
- DIAGNOSTICSSFI SYSTEM (2AZ-FE)
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DTC P0031 OXYGEN (A/F) SENSOR HEATER CONTROL
CIRCUIT LOW (BANK 1 SENSOR 1)
DTC P0032 OXYGEN SENSOR HEATER CONTROL
CIRCUIT HIGH (BANK 1 SENSOR 1)
HINT:
Although the title (DTC description) says ºoxygen sensorº, this DTC is related to the ºA/F sensorº.
CIRCUIT DESCRIPTION
Refer to DTC P2195 on page 05-269.
HINT:
The ECM provides a pulse width modulated control circuit to adjust current through the heater. The A/F sen-
sor heater circuit uses a relay on the +B side of the circuit.
DTC No.DTC Detection ConditionTrouble Area
P0031Heater current of 0.8 A or less when heater operates
(1 trip detection logic)

Open in heater circuit of A/F sensor

A/F sensor heater

EFI relay

ECM
P0032Heater current exceeds 10 A when heater operates
(1 trip detection logic)

Short in heater circuit of A/F sensor

A/F sensor heater

EFI relay

ECM
HINT:
Sensor 1 is the sensor closest to the engine assembly.
05ET1-06

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MONITOR DESCRIPTION
The ECM uses A/F sensor information to keep the air/fuel ratio close to the stoichiometric ratio. This maxi-
mizes the catalytic converter's ability to purify exhaust gas. The sensor detects oxygen levels in the exhaust
gas and sends this signal to the ECM.
The inner surface of the sensor element is exposed to outside air. The outer surface of the sensor element
is exposed to exhaust gas. The sensor element is made of platinum coated zirconia and includes an inte-
grated heating element. The zirconia element generates small voltage when there is a large difference in
the oxygen concentrations of the exhaust and the outside air. The platinum coating amplifies the voltage
generation. When heated, the sensor becomes very efficient. If the temperature of the exhaust is low, the
sensor will not generate useful voltage signals without supplemental heating. The ECM regulates the sup-
plemental heating using a duty-cycle approach to regulate the average current in the heater element. If the
heater current is out of the normal range, the sensor's output signals will be inaccurate and the ECM cannot
regulate the A/F ratio properly.
When the heater current is out of the normal operating range, the ECM interprets this as a malfunction and
sets a DTC.
MONITOR STRATEGY
Related DTCsP0031: A/F sensor heater range check (Low current)
P0032: A/F sensor heater range check (High current)
Required sensors / components (Main)A/F sensor heater
Required sensors / components (Related)-
Frequency of operationContinuous
Duration10 sec.
MIL operationImmediate
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
All:
The monitor will run whenever these DTCs are not presentSee page 05-16
P0031:
Battery voltageLess than 10.5 V
A/F sensor heater duty ratio50 % or more
Time after engine start10 sec. or more
P0032:
Time after engine start10 sec. or more
TYPICAL MALFUNCTION THRESHOLDS
P0031:
A/F sensor heater currentLess than 0.8 A
P0032:
A/F sensor heater currentMore than 10 A
COMPONENT OPERATING RANGE
A/F sensor heater current1.8 to 3.4 A at 20°C (68°F)

A52607
AF-AF+
A6
A/F sensor
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MONITOR RESULT
Refer to page 05-24 for detailed information.
The test value and test limit information are described as shown in the following table. Check the monitor
result and test values after performing the monitor drive pattern (see page 05-26).

TID (Test Identification Data) is assigned to each emissions-related component.

TLT (Test Limit Type):
If TLT is 0, the component is malfunctioning when the test value is higher than the test limit.
If TLT is 1, the component is malfunctioning when the test value is lower than the test limit.

CID (Component Identification Data) is assigned to each test value.

Unit Conversion is used to calculate the test value indicated on generic OBD ll scan tools.
TID $07: A/F sensor heater
TLTCIDUnit ConversionDescription of Test DataDescription of Test Limit
1$01Multiply by 0.00017
(A)Maximum heater currentMalfunction criterion for A/F sensor heater
WIRING DIAGRAM
Refer to DTC P2195 on page 05-269.
INSPECTION PROCEDURE
HINT:
Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the
engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help deter-
mine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean
or rich, and other data from the time the malfunction occurred.
1 INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)
(a) Disconnect the A6 A/F sensor connector.
(b) Measure the resistance between the terminals of the A/F
sensor.
Standard:
Tester ConnectionConditionSpecified Condition
1 (HT) - 2 (+B)20C (68F)1.8 to 3.4 W
1 (HT) - 4 (AF-)-10 kW or higher
NG REPLACE AIR FUEL RATIO SENSOR
OK

12
34
A81695
A76787A85433
Wire Harness Side
A6
A/F Sensor
HT
+B
HA1AE8
ECM
12
34
A90291
A76787A90920
Wire Harness Side
A6
A/F Sensor
HT
+B
EFI Relay
Engine Room J/B
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4 CHECK WIRE HARNESS (ECM - A/F SENSOR, A/F SENSOR - EFI RELAY)
(a) Check the wire harness between the ECM and A/F sen-
sor.
(1) Disconnect the E8 ECM connector.
(2) Disconnect the A6 A/F sensor connector.
(3) Measure the resistance of the wire harness side
connectors.
Standard:
Tester ConnectionSpecified Condition
A6-1 (HT) - E8-5 (HA1A)Below 1 W
A6-1 (HT) or E8-5 (HA1A) - Body ground10 kW or higher
(b) Check the wire harness between the A/F sensor and EFI
relay.
(1) Disconnect the A6 A/F sensor connector.
(2) Remove the EFI relay from the engine room J/B.
(3) Measure the resistance of the wire harness side
connectors.
Standard:
Tester ConnectionSpecified Condition
A6-2 (+B) - J/B EFI relay terminal 3Below 1 W
A6-2 (+B) or J/B EFI relay terminal 3 -Body ground10 kW or higher
NG REPAIR OR REPLACE HARNESS AND
CONNECTOR
OK
REPLACE ECM (See page 10-9)

A90346
Reference
Heater
Sensor
Duty
Control ECM
From
Battery
EFI NO. 1
FuseEFI Relay
+B HT
EFI NO. 2
Fuse
MREL OX1B HT1B Heated Oxygen Sensor
OB1- OX E1 05-76
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2005 HIGHLANDER REPAIR MANUAL (RM1144U)
DTC P0037 OXYGEN SENSOR HEATER CONTROL
CIRCUIT LOW (BANK 1 SENSOR 2)
DTC P0038 OXYGEN SENSOR HEATER CONTROL
CIRCUIT HIGH (BANK 1 SENSOR 2)
CIRCUIT DESCRIPTION
Refer to DTC P0136 on page 05-1 18.
HINT:
The ECM provides a pulse width a modulated control circuit to adjust current through the heater. The oxygen
sensor heater circuit uses a relay on the +B side of the circuit.
DTC No.DTC Detection ConditionTrouble Area
P0037
Heater current of less than 0.3 A when the heater operates
with +B greater than 10.5 V
(1 trip detection logic)
Open or short in heater circuit of heated oxygen sensor

Heated oxygen sensor heater

EFI relay

ECM
P0038Heater current exceeds 2 A when heater operates
(1 trip detection logic)
Same as DTC No. P0037
HINT:
Sensor 2 is the sensor farthest away from the engine assembly.
MONITOR DESCRIPTION
The sensing portion of the heated oxygen sensor has a zirconia element that is used to detect oxygen con-
centration in the exhaust. If the zirconia element is at the proper temperature and the difference of the oxy-
gen concentration between the inside and outside surface of the sensor is large, the zirconia element will
generate voltage signals. In order to increase the oxygen concentration detecting capacity in the zirconia
element, the ECM supplements the heat from the exhaust with heat from a heating element inside the sen-
sor. When current in the sensor is out of the standard operating range, the ECM interprets this as a fault in
the heated oxygen sensor and sets a DTC.
Example:
The ECM will set a high current DTC if the current in the sensor is more than 2 A when the heater is OFF.
Similarly, the ECM will set a low current DTC if the current is less than 0.25 A when the heater is ON.
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MONITOR STRATEGY
Related DTCsP0037: HO2S heater range check (Low current)
P0038: HO2S heater range check (High current)
Required sensors / components (Main)Heated oxygen sensor (HO2S) heater
Required sensors / components (Related)Vehicle speed sensor (VSS)
Frequency of operationContinuous
Duration0.3 sec.
MIL operationImmediate
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
All:
The monitor will run whenever these DTCs are not presentSee page 05-16
P0037:
Battery voltage10.5 V or more
EngineRunning
StarterOFF
Intrusive heatingNot operated
P0038 (Case 1):
Battery voltage10.5 V or more
EngineRunning
StarterOFF
Intrusive heatingNot operated
P0038 (Case 2):
Battery voltage10.5 V or more
All heater is turned OFF and intrusive heating is operated
when the following conditions are metCondition 1 and 2
1. HeaterON
2. Heater current2 A or more
TYPICAL MALFUNCTION THRESHOLDS
P0037:
HO2S heater current intrusive heatingLess than 0.3 A
P0038 (Case 1):
HO2S heater current2 A or more
P0038 (Case 2):
HO2S heater current intrusive heatingMore than 2 A
COMPONENT OPERATING RANGE
HO2S heater current0.4 to 1 A (when engine is idle, warmed-up and battery voltage is 11 to 14 V)