2001 TOYOTA SEQUOIA O2 sensor

A23557
ECM A42
Air Pressure Sensor
VC
AIP
E2
E8 E8 E8
2832 23
VC
AIP
E2EB4
EB4
EB4G±B G±B
B±Y
B±Y
G±W
G±W6 5 15 V
B17412
E8
E2AIP VC
B17439
Wire Harness Side:
Pressure Sensor Connector
A42
E2
AIP VC
DI±424
± DIAGNOSTICSENGINE
618 Author: Date:
2005 SEQUOIA (RM1146U)
WIRING DIAGRAM
INSPECTION PROCEDURE
1 Check for open and short in harness and connector between pressure sensor
and ECM (See page IN±35).
PREPARATION:
(a) Remove the intake manifold (see page EM±36).
(b) Disconnect the A42 pressure sensor connector.
(c) Disconnect the E8 ECM connector.
CHECK:
Measure the resistance between the wire harness side connec-
tors.
OK:
Standard:
Tester ConnectionSpecified Condition
VC (A42±1) ± VC (E8±23)
AIP (A42±2) ± AIP (E8±32)
E2 (A42±3) ± AIP (E8±28)
Below 1 W
VC (A42±1) or VC (E8±23) ±
Body ground
AIP (A42±2) or AIP (E8±32) ±
Body ground
10 kW or higher
NG Repair or replace harness and connector.
OK

B17434
Pressure Gauge
Pressure Sensor
± DIAGNOSTICSENGINE
DI±425
619 Author: Date:
2005 SEQUOIA (RM1146U)
2 Inspect pressure sensor.
PREPARATION:
(a) Remove the intake manifold (see page EM±36).
(b) Connect the pressure gauge to the pressure sensor as
shown in the illustration.
(c) Connect the hand±held tester to the DLC3 on the vehicle.
(d) Turn the ignition switch ON and push the hand±held tes-
ter main switch ON (Do not start engine).
(e) Select the following items: DIAGNOSIS / ENHANCED
OBD II / DATA LIST / 2ND AIR PRESS.
CHECK:
Check that the pressure displayed on the hand±held tester fluc-
tuates when applying the pressure to the pressure sensor with
the pressure gauge.
OK:
Pressure fluctuates in response to the pressure ap-
plied with pressure gauge.
NG Replace pressure sensor (See page EC±22).
OK
Replace ECM (See page SF±80).

DI±426
± DIAGNOSTICSENGINE
620 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P2444 Secondary Air Injection System Pump Stuck
ON Bank 1
DTC P2445 Secondary Air Injection System Pump Stuck
OFF Bank 1
CIRCUIT DESCRIPTION
Refer to DTC P0412 on page DI±234.
DTC No.DTC Detection ConditionTrouble Area
P2444
Air pump stuck ON.
The secondary air pressure is more than 5 kPa (38 mmHg)
despite the ECM ordering the air pump to turn off.
(2 trip detection logic)
Short in air pump circuit

Air injection driver

Pressure sensor

Open or short in pressure sensor circuit

ECM
P2445
Air pump stuck OFF or air injection volume is insufficient.
The amount of air flow is below the criteria.
(The secondary air pressure is less than specified value de-
spite the ECM ordering the air pump turn ON.)
(2 trip detection logic)

Air pump fuse

Vacuum hose

Air pump assembly

Air injection driver

Open in air pump circuit

Air injection system piping

Pressure sensor

Open or short in pressure sensor circuit

ECM
MONITOR DESCRIPTION
P2444:
The ECM observes the pressure in the secondary air passage using the pressure sensor located on the air
switching valve in the secondary air injection system. The sensor measures the pressure in the secondary
air passage and sends a signal to the ECM.
If the pressure level from the sensor exceed a certain level despite the ECM turning off the air pump, the
ECM interprets this as a fault in the secondary air injection system and sets a DTC.
P2445:
The ECM calculates the amount of air flow in the secondary air system based on the output values of the
pressure sensor and mas air flow meter.
The ECM determines whether the amount of air flow is normal or not according to the calculated value. When
the amount of air flow is below the criteria, the ECM stores the DTC and illuminates the MIL.
DIDMU±01

± DIAGNOSTICSENGINE
DI±427
621 Author: Date:
2005 SEQUOIA (RM1146U)
MONITOR STRATEGY
P2444Air pump is stuck ON
RltdDTCAir pump is stuck OFFRelated DTCsP2445Air flow volume is insufficientP2445
Air pressure sensor is stuck
Required sensors/componentsAIR pump, AIR pressure sensor
Frequency of operationContinuous
Duration
P2444 (Air pump is stuck ON): 20 sec.
P2445 (Air pump is stuck OFF): 8 sec.
P2445 (Air flow volume is insufficient): 8 sec.
P2445 (Air pressure sensor is stuck:) 1.5 sec.
MIL operation2 driving cycles
Sequence of operationNone
TYPICAL ENABLING CONDITIONS
P2444: Air pump is stuck ON
ItSpecificationItemMinimumMaximum
The monitor will run whenever this DTC is
not presentSee page DI±18
Atmospheric pressure570 mmHg (76 kPa)±
Battery voltage11.5 V±
Time after secondary air injection out of
operation10 sec.±
AIR pumpOFF
Air switching valve No. 2 (Bank 1)OFF
Air switching valve No. 2 (Bank 2)OFF
Engine RPM±3,750 rpm
Air injection pressure sensor failNot detected
P2445: Air pump is stuck OFF or air insufficient
ItSpecificationItemMinimumMaximum
The monitor will run whenever this DTC is
not presentSee page DI±18
Atmospheric pressure570 mmHg (76 kPa)±
Battery voltage11.5 V±
Time after secondary air injection out of
operation6 sec.±
AIR pumpON
Air switching valveON
Air switching valve No. 2 (Bank 1)ON
Air switching valve No. 2 (Bank 2)ON
Engine RPM±3,750 rpm
Delay time after engine started6 sec.±
Air injection pressure sensor failNot detected

DI±428
± DIAGNOSTICSENGINE
622 Author: Date:
2005 SEQUOIA (RM1146U)
P2445: Air pressure sensor is stuck
ItSpecificationItemMinimumMaximum
The monitor will run whenever this DTC is
not presentSee page DI±18
ECT at engine start±5°C (41°F)
IAT at engine start±15°C (5°F)±
Time that ECT is 80°C (176°F) or higher10 to 60 min.
Cumulative intake air amount172 g±
One of the following conditions is metCondition 1, 2 or 3
1. Vehicle speed80 km/h (49.7 mile)±
2. Engine RPM0 rpm±
3. Throttle position0 deg
Air switching valveOFF
Air switching valve No. 2 (Bank 1)OFF
Air switching valve No. 2 (Bank 2)OFF
Air injection pressure sensor failNot detected
TYPICAL MALFUNCTION THRESHOLDS
P2444: Air pump is stuck ON
Detection CriteriaThreshold
Smoothed pressure5 kPa (113 mmHg) or more
(when AI OFF (Air pump OFF, all of air switching valves are OFF)
P2445: Air pump is stuck OFF or air insufficient
Detection CriteriaThreshold
Either of the following conditions is metCondition 1 or 2
1. Air flow value100 L/min. or less
2. Smoothed pressureLess than 1 kPa (7.5 mmHg)
(when AI ON (Air pump ON, all of air switching valves are ON)
P2445: Air pressure sensor is stuck
Detection CriteriaThreshold
Detected times of identifying condition 1 is met4 times or more
Air pressure change5 kPa (113 mmHg) or more

B17435Vacuum Hose
DI±432
± DIAGNOSTICSENGINE
626 Author: Date:
2005 SEQUOIA (RM1146U)
3 Check whether DTC output recurs.
PREPARATION:
(a) Start the engine and warm it up.
(b) Turn the ignition switch OFF.
(c) Connect a hand±held tester to the DLC3.
(d) Turn the ignition switch to ON and turn the tester ON.
(e) Clear the DTCs (see page DI±43).
(f) Start the engine.
CHECK:
(a) Perform SYSTEM CHECK to operate the air injection system.
Select the following menu items: DIAGNOSIS/ENHANCED OBD II/SYSTEM CHECK/AIR INJ
CHECK/AUTOMATIC OPERATION
(b) After operating the secondary air injection system, confirm the pending codes for the secondary air
injection system by selecting the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO
/ PENDING CODES.
(c) Read DTCs and check that no DTC is set.
OK:
DTC P2444 or P2445 for the secondary air injection system is not output.
NG Go to step 4.
OK
Check for intermittent problems
(See page DI±11).
4 Check vacuum hose.
CHECK:
(a) Remove the intake manifold (see page EM±36).
(b) Check the vacuum hose connection between the pres-
sure sensor and air switching valve.
OK:
The vacuum hose is securely connected.
CHECK:
(a) Check the vacuum hose for blockage or damage.
OK:
The vacuum hose has no blockage or damage.
NG Repair or replace vacuum hose.
OK

B17434
Pressure GaugePressure Sensor
B17436
± DIAGNOSTICSENGINE
DI±433
627 Author: Date:
2005 SEQUOIA (RM1146U)
5 Inspect ECM (air voltage).
PREPARATION:
(a) Remove the intake manifold (see page EM±36).
(b) Connect the pressure gauge to the pressure sensor as
shown in the illustration.
(c) Connect the hand±held tester to the DLC3 on the vehicle.
(d) Turn the ignition switch ON and push the hand±held tes-
ter main switch ON (Do not start engine).
(e) Select the following items: DIAGNOSIS / ENHANCED
OBD II / DATA LIST / AIR PUMP PRS.
CHECK:
Check that the pressure displayed on the hand±held tester fluc-
tuates when applying the pressure to the pressure sensor with
the pressure gauge.
OK:
Pressure fluctuates in response to the pressure ap-
plied with the pressure gauge.
NG Replace pressure sensor.
OK
6 Check connection of all air injection system piping and hoses.
CHECK:
(a) Remove the intake manifold (see page EM±36).
(b) Check that all the pipes and hoses between the air pump
and air switching valve are securely connected.
OK:
All the air injection pipes and hoses are securely con-
nected.
CHECK:
(a) Check the pipe and hoses for blockage or damage.
OK:
The air injection system pipes and hoses have no
blockage and damage.
NG Repair or replace air injection system piping.
OK

A23475
Pressure GaugePressure Sensor
± DIAGNOSTICSENGINE
DI±439
633 Author: Date:
2005 SEQUOIA (RM1146U)
12 Check air pump operation.
PREPARATION:
(a) Connect the pressure gauge to the air switching valve as
shown in the illustration.
(b) Connect the hand±held tester to the DLC3.
(c) Turn the ignition switch ON and turn the tester ON.
CHECK:
(a) When the air pump is operated using the hand±held tes-
ter, measure the secondary air injection system pressure.
(b) Select the following menu items: DIAGNOSIS/EN-
HANCED OBD II/ACTIVE TEST/AIR INJ CHECK/MANU-
AL OPERATION/OPERATION 3
HINT:
OPERATION 2: AP:ON, EASV:CLOSE, ASV1:CLOSE,
ASV2:CLOSE
NOTICE:
This test only allows technicians to operate the AI system
for 5 seconds. Furthermore, the test can be performed 4
times a trip. If the test is repeated, intervals of at least 30
seconds are required between tests.
While the AI system operation using the hand±held tester
is prohibited, the tester displays the prohibition (WAIT or
ERROR). If the ERROR (AI STATUS NG) is displayed on the
tester, stop the engine for 10 minutes and then try again..
OK:
Standard:
25 to 30 kPa or more
NG Replace air pump.
OK