2001 TOYOTA SEQUOIA check engine

A02852
A23658
± DIAGNOSTICSENGINE
DI±83
277 Author: Date:
2005 SEQUOIA (RM1146U)
5 Check VVT controller assembly.
PREPARATION:
(a) Remove the timing belt (See page EM±16).
(b) Remove the cylinder head cover.
(c) Remove the OCV (See page SF±46).
(d) Drain the oil in the VVT controller assembly
(See page EM±36).
CHECK:
Check whether the oil in VVT controller assembly is drained or
not.
OK:
Standard:
The oil in VVT controller assembly is drained.
NG Replace VVT controller assembly, and then go
to step 6.
OK
6 Check oil control valve filter.
PREPARATION:
(a) Remove the cylinder head cover.
(b) Remove the camshaft bearing cap and OCV filter.
CHECK:
Check that the filter is not clogged.
OK:
The filter is not clogged.
NG Repair or replace.
OK

DI±84
± DIAGNOSTICSENGINE
278 Author: Date:
2005 SEQUOIA (RM1146U)
7 Check whether or not DTC P0010, P0012, P0021 or P0022 is stored.
PREPARATION:
(a) Clear the DTC (See page DI±43).
(b) Perform simulation test.
CHECK:
Check whether or not DTC P0011, P0012, P0021 or P0022 is stored (See page DI±43).
OK:
Standard: DTC P0011, P0012, P0021 or P0022 is not stored.
OK VVT system is OK.*
*: DTC P0011, P0012, P0021 or P0022 is also output when a
foreign object is detected in some parts of the system in the en-
gine oil, and then the system returns to normal in a short time.
As ECM is controlled to eject a foreign object, there is no prob-
lem on the VVT. There is also no problem on the VVT as the oil
filter should catch the foreign object in the engine oil.
NG
Replace ECM.

A02961
V5
VVT Sensor (Bank 1)ECM
1
2R
G
Y
LVVL+
VVL±
VVR+
E5 18
19
19
18
VVR±
1
2E5
E4
E4 V6
VVT Sensor (Bank 2)
± DIAGNOSTICSENGINE
DI±87
281 Author: Date:
2005 SEQUOIA (RM1146U)
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:

If DTC P0016 is displayed, check left bank VVT sensor.

If DTC P0018 is displayed, check right bank VVT sensor.

Read freeze frame data using hand±held tester or OBD II scan tool. Because freeze frame records
the engine conditions when the malfunction is detected. When troubleshooting, it is useful for deter-
mining whether the vehicle was running or stopped, the engine was warmed up or not, the air±fuel ratio
was lean or rich, etc. at the time of the malfunction.
1 Check valve timing (Check for loose and jumping teeth of timing belt) (See page
EM±16).
NG Adjust valve timing (Repair or replace timing
belt).
OK
Replace ECM (See page SF±80).

± DIAGNOSTICSENGINE
DI±89
283 Author: Date:
2005 SEQUOIA (RM1146U)
HINT:

Bank 1 refers to the bank that includes cylinder No.1.

Bank 2 refers to the bank that does not include cylinder No.1.

Sensor 1 refers to the sensor closest to the engine assembly.

Sensor 2 refers to the sensor farthest away from the engine assembly.
MONITOR DESCRIPTION
The ECM uses the Air±Fuel Ratio sensor (A/F sensor) information to regulate the air±fuel ratio close to the
stoichiometric ratio. This maximizes the catalytic converter's ability to purify exhaust gases. The sensor de-
tects 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 a 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 can
not regulate the air±fuel 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
P0031A/F sensor heater (Bank 1) range check (Low
current)
RltdDTC
P0032A/F sensor heater (Bank 1) range check (High
current)
Related DTCs
P0051A/F sensor heater (Bank 2) range check (Low
current)
P0052A/F sensor heater (Bank 2) range check (High
current)
Rid / tMain sensors/componentsA/F sensor heaterRequired sensors/componentsRelated sensors/components±
Frequency of operationContinuous
Duration10 sec.
MIL operationImmediate
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
ItSpecificationItemMinimumMaximum
The monitor will run whenever these
DTCs are not presentSee page DI±18
P0031, P0051 (Low current):
Battery voltage10.5 V±
A/F sensor heater duty ratio50%±
Time after engine start10 sec.±

B17396
HT +B
AF± AF+ Sensor 1A/F Sensor Component Side:
Front View
DI±90
± DIAGNOSTICSENGINE
284 Author: Date:
2005 SEQUOIA (RM1146U) P0032, P0052 (High current):
Time after engine start10 sec.±
TYPICAL MALFUNCTION THRESHOLDS
Detection CriteriaThreshold
P0031, P0051 (Low current):
A/F sensor heater currentLess than 0.8 A
P0032, P0052 (High current):
A/F sensor heater currentMore than 10 A
COMPONENT OPERATING RANGE
ParameterStandard Value
A/F sensor heater current1.8 to 3.4 A at 20°C (68°F)
WIRING DIAGRAM
Refer to DTC P2195 on page DI±383.
INSPECTION PROCEDURE
HINT:
Read freeze frame data using a hand±held tester or OBD II scan tool. Freeze frame data record the engine
condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if
the vehicle was moving or stationary, 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 Check resistance of air±fuel ratio (A/F) sensor heater.
PREPARATION:
Disconnect the air±fuel ratio (A/F) sensor connector.
CHECK:
Measure resistance between the terminals of the A/F sensor
connector.
OK:
Standard:
Tester ConnectionSpecified Condition
HT (1) ± +B (2)1.8 W to 3.4 W at 20C (68F)
HT (1) ± AF± (4)10 kW or higher
NG Replace air±fuel ratio (A/F) sensor.
OK

A19288
B17411
HA1A
E7HA2A
± DIAGNOSTICSENGINE
DI±91
285 Author: Date:
2005 SEQUOIA (RM1146U)
2 Check A/F relay.
PREPARATION:
Remove the A/F relay from the engine room R/B No.2.
CHECK:
Inspect the A/F relay.
OK:
Standard:
Terminal No.ConditionSpecified Condition
3 ± 5Always10 KW or higher
3 ± 5Apply B+ between
terminals 1 and 2Below 1 W
NG Replace A/F relay.
OK
3 Check voltage between terminals HA1A, HA2A of ECM connectors and body
ground.
PREPARATION:
Turn the ignition switch ON.
CHECK:
Measure the voltage between terminals of the ECM connectors
and body ground.
HINT:

Connect terminal HA1A to the bank 1 sensor 1.

Connect terminal HA2A to the bank 2 sensor 1.
OK:
Standard:
Tester ConnectionSpecified Condition
HA1A (E7±2) ± Body ground9 V to 14 V
HA2A (E7±1) ± Body ground9 V to 14 V
OK Replace ECM (See page SF±80).
NG

A23659
Wire Harness Side:
HT
A38
Sensor 1A/F Sensor Connector
Front View
+B A39
B17415
E7ECM Connector
HA1A
HA2A
H24253
A/F Relay
Engine Room R/B No.2:
DI±92
± DIAGNOSTICSENGINE
286 Author: Date:
2005 SEQUOIA (RM1146U)
4 Check for open and short in harness and connector between ECM and A/F sen-
sor.
PREPARATION:
(a) Turn the ignition switch to OFF.
(b) Disconnect the A38 or A39 A/F sensor connector.
(c) Disconnect the E7 ECM connector.
CHECK:
Check the resistance.
OK:
Standard (Check for open):
Tester ConnectionsSpecified Conditions
HT (A38±1) ± HA1A (E7±2)
HT (A39±1) ± HA2A (E7±1)Below 1 W
Standard (Check for short):
Tester ConnectionsSpecified Conditions
HT (A38±1) or HA1A (E7±2) ± Body ground
HT (A39±1) or HA2A (E7±1) ± Body ground10 kW or higher
PREPARATION:
(a) Turn the ignition switch to OFF.
(b) Disconnect the A38 or A39 A/F sensor connector.
(c) Remove A/F relay from engine room R/B No.2.
CHECK:
Check the resistance.
OK:
Standard (Check for open):
Tester ConnectionsSpecified Conditions
+B (A38±2) ± A/F relay (3)
+B (A39±2) ± A/F relay (3)Below 1 W
Standard (Check for short):
Tester ConnectionsSpecified Conditions
+B (A38±2) or A/F relay (3) ± Body ground
+B (A39±2) or A/F relay (3) ± Body ground10 kW or higher
NG Repair or replace harness or connector.
OK
Check for intermittent problems
(See page DI±11).

± DIAGNOSTICSENGINE
DI±95
289 Author: Date:
2005 SEQUOIA (RM1146U)DTC No.
DTC Detecting ConditionTrouble Area
P0037Heater current is 0.25 A or less when the heater operates with

Open in heater circuit of heated oxygen sensor

Heated ox
ygen sensor heaterP0037
P0057
Heater current is 0.25 A or less when the heater o erates with
more than 10.5 V positive battery voltage

Heated oxygen sensor heater

EFI relay

ECM
P0038
P0058When heater operates, heater current exceeds 2.0 A

Short in heater circuit of heated oxygen sensor

Heated oxygen sensor heater

EFI relay

ECM
HINT:

Bank 1 refers to bank that includes cylinder No. 1.

Bank 2 refers to bank that does not includes cylinder No. 1.

Sensor 1 refers to the sensor closer to the engine assembly.

Sensor 2 refers to the sensor farther away from the engine assembly.
MONITOR DESCRIPTION
The sensing portion of the heated oxygen sensor has a zirconia element which is used to detect oxygen
concentration in the exhaust. If the zirconia element is at the proper temperature and difference of the oxy-
gen concentration between the inside and outside surface of sensor is large, the zirconia element will gener-
ate 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 sensor. 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 2.0 A when the heater is OFF.
Similarly, the ECM will set a low current DTC if the current is less than 0.3 A when the heater is ON.
MONITOR STRATEGY
P0037Rear HO2S heater (Bank 1) range check (Low
Current)
RltdDTC
P0038Rear HO2S heater (Bank 1) range check (High
Current)
Related DTCs
P0057Rear HO2S heater (Bank 2) range check (Low
Current)
P0058Rear HO2S heater (Bank 2) range check (High
Current)
Rid / tMain sensors/componentsHO2S heaterRequired sensors/componentsRelated sensors/componentsVehicle speed sensor (VSS)
Frequency of operationContinuous
Duration0.3 sec.
MIL operationImmediate
Sequence of operationNone