2001 TOYOTA SEQUOIA catalytic

A23542
Normal Catalyst Deteriorated Catalyst
Waveform of
A/F Sensor
in front of TWC
Waveform of
HO2 Sensor
behind TWCVoltage output when active air±fuel ratio control not performed
3.5 V
3.0 V
1.0 V
0 V
10 seconds 10 seconds DI±252
± DIAGNOSTICSENGINE
446 Author: Date:
2005 SEQUOIA (RM1146U)
HINT:
If either of the voltage outputs of the Air±Fuel Ratio (A/F) or Heated Oxygen (HO2) sensors does not
fluctuate, or either of the sensors makes a noise, the sensor may be malfunctioning.
If the voltage outputs of both the sensors remain lean or rich, the air±fuel ratio may be extremely lean
or rich. In such cases, perform the following A/F CONTROL using a hand±held tester.
If the Three±Way Catalytic Converter (TWC) has deteriorated, the HO2 sensor (located behind the
TWC) voltage output fluctuates up and down frequently, even under normal driving conditions (active
air±fuel ratio control is not performed).
A/F CONTROL
HINT:
Hand±held tester only:
Malfunctioning areas can be identified by performing the A/F CONTROL function provided in the ACTIVE
TEST. The A/F CONTROL function can help to determine whether the Air±Fuel Ratio (A/F) sensor, Heated
Oxygen (HO2) sensor and other potential trouble areas are malfunctioning.
The following instructions describe how to conduct the A/F CONTROL operation using a hand±held tester.
(1) Connect a hand±held tester to the DLC3.
(2) Start the engine and turn the tester ON.
(3) Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
(4) On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / ACTIVE
TEST / A/F CONTROL.
(5) Perform the A/F CONTROL operation with the engine in an idling condition (press the RIGHT
or LEFT button to change the fuel injection volume).
(6) Monitor the voltage outputs of the A/F and HO2 sensors (AFS B1S1 and OS2 B1S2) displayed
on the tester.
HINT:
The A/F CONTROL operation lowers the fuel injection volume by 12.5 % or increases the injection
volume by 25 %.
Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

Status
A/F S1Status
O2S S2A/F Condition and A/F and
HO2 Sensors ConditionMisfiresMain Suspected Trouble Areas
Proceed To
LeanLean/Rich Normal
± Three±way Catalytic Converter (TWC)
 Gas leakage from exhaust systemA
A A B
B
C
C Lean/Rich
Lean/Rich
Lean/Rich
Lean/Rich Lean/Rich
Lean Lean Rich
Rich
Rich
Rich LeanA/F sensor malfunction
A/F sensor malfunction
HO2 sensor malfunction
HO2 sensor malfunction
Actual air±fuel ratio lean
Actual air±fuel ratio lean
±
±
±
±
May occur A/F senso
r
 A/F sensor
 HO2 sensor
 HO2 sensor
 Gas leakage from exhaust system
 Gas leakage from exhaust system
 Gas leakage from exhaust system
 Gas leakage from exhaust system  Extremely rich or lean actual air±fuel ratio± Extremely rich or lean actual air±fuel ratio
± DIAGNOSTICSENGINE
DI±255
449 Author: Date:
2005 SEQUOIA (RM1146U)
Standard:
Tester Display
(Sensor)Injection VolumesStatusVoltages
AFS B1S1
(A/F)+25 %RichLess than 3.0
AFS B1S1
(A/F)±12.5 %LeanMore than 3.35
O2S B1S2
(HO2)+25 %RichMore than 0.55
O2S B1S2
(HO2)±12.5 %LeanLess than 0.4
RESULT:
Lean: During A/F CONTROL, the A/F sensor output voltage (AFS) is consistently more than 3.35 V, and the
HO2 sensor output voltage (O2S) is consistently less than 0.4 V.
Rich: During A/F CONTROL, the AFS is consistently less than 3.0 V, and the O2S is consistently more than
0.55 V.
B Check and replace A/F sensor.
C Check and replace heated oxygen sensor and
check and repair exhaust gas leakage.
A

DI±256
± DIAGNOSTICSENGINE
450 Author: Date:
2005 SEQUOIA (RM1146U)
3 Check gas leakage on exhaust system.
OK:
No exhaust gas leakage.
NG Repair or replace exhaust gas leakage point.
OK
Replace front and rear three±way catalytic
converter in the bank a malfunction is de-
tected.

± DIAGNOSTICSENGINE
DI±383
577 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P2195 Oxygen (A/F) Sensor Signal Stuck Lean
(Bank 1 Sensor 1)
DTC P2196 Oxygen (A/F) Sensor Signal Stuck Rich
(Bank 1 Sensor 1)
DTC P2197 Oxygen (A/F) Sensor Signal Stuck Lean
(Bank 2 Sensor 1)
DTC P2198 Oxygen (A/F) Sensor Signal Stuck Rich
(Bank 2 Sensor 1)
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 lo-
cated near the engine assembly.
DIDFT±01

DI±402
± DIAGNOSTICSENGINE
596 Author: Date:
2005 SEQUOIA (RM1146U)
DTC P2238 Oxygen Sensor Pumping Current Circuit
Low (For A/F Sensor)(Bank 1 Sensor1)
DTC P2239 Oxygen Sensor Pumping Current Circuit
High (For A/F Sensor)(Bank 1 Sensor1)
DTC P2241 Oxygen Sensor Pumping Current Circuit
Low (For A/F Sensor)(Bank 2 Sensor1)
DTC P2242 Oxygen Sensor Pumping Current Circuit
High (For A/F Sensor)(Bank 2 Sensor1)
DTC P2252 Oxygen Sensor Reference Ground Circuit
Low (For A/F Sensor)(Bank 1 Sensor1)
DTC P2253 Oxygen Sensor Reference Ground Circuit
High (For A/F Sensor)(Bank 1 Sensor1)
DTC P2255 Oxygen Sensor Reference Ground Circuit
Low (For A/F Sensor)(Bank 2 Sensor1)
DTC P2256 Oxygen Sensor Reference Ground Circuit
High (For A/F Sensor)(Bank 2 Sensor1)
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 lo-
cated near the engine assembly.
DIDFU±01

DIDIJ±01
± DIAGNOSTICSAUTOMATIC TRANSMISSION
DI±517
711 Author: Date:
2005 SEQUOIA (RM1146U)
TOYOTA PART AND SYSTEM NAME LIST
This reference list indicates the part names used in this manual along with their definitions.
Part and system nameDefinition
Toyota HCAC system, Hydrocarbon adsorptive Catalyst
(HCAC) system, HC adsorptive three±way catalystHC adsorptive three±way catalytic converter
Variable Valve Timing sensor, VVT sensorCamshaft position sensor
Variable valve timing system, VVT systemCamshaft timing control system
Camshaft timing oil control valve, Oil control valve OCV,
VVT, VSVCamshaft timing oil control valve
Variable timing and lift, VVTLCamshaft timing and lift control
Crankshaft position sensor ºAºCrankshaft position sensor
Engine speed sensorCrankshaft position sensor
THAIntake air temperature
Knock control moduleEngine knock control module
Knock sensorEngine knock sensor
Mass or volume air flow circuitMass air flow sensor circuit
Vacuum sensorManifold air pressure sensor
Internal control module, Control module, Engine control
ECU, PCMPower train control module
FC idleDeceleration fuel cut
Idle air control valveIdle speed control
VSV for CCV, Canister close valve VSV for canister controlEvaporative emissions canister vent valve
VSV for EVAP, Vacuum switching valve assembly No. 1,
EVAP VAV, Purge VSVEvaporative emissions canister purge valve
VSV for pressure switching valve, Bypass VSVEvaporative emission pressure switching valve
Vapor pressure sensor, EVAP pressure sensor, Evaporative
emission control system pressure sensorFuel tank pressure sensor
Charcoal canisterEvaporative emissions canister
ORVR systemOn±board refueling vapor recovery system
Intake manifold runner controlIntake manifold tuning system
Intake manifold runner valve, IMRV, IACV (runner valve)Intake manifold tuning valve
Intake control VSVIntake manifold tuning solenoid valve
AFSAir fuel ratio sensor
O2 sensorHeater oxygen sensor
Oxygen sensor pumping current circuitOxygen sensor output signal
Oxygen sensor reference ground circuitOxygen sensor signal ground
Accel position sensorAccelerator pedal position sensor
Throttle actuator control motor, Actuator control motor, Elec-
tronic throttle motor, Throttle control motorElectronic throttle actuator
Electronic throttle control system, Throttle actuator control
systemElectronic throttle control system
Throttle/pedal position sensor, Throttle/pedal position switch,
Throttle position sensor/switchThrottle position sensor
Turbo press sensorTurbocharger pressure sensor
Turbo VSVTurbocharger pressure control solenoid valve
P/S pressure switchPower±steering pressure switch
VSV for ACMActive control engine mount
Speed sensor, Vehicle speed sensor ºAº, Speed sensor for
skid control ECUVehicle speed sensor
ATF temperature sensor, Trans. fluid temp. sensor, ATF
temperature sensor ºAºTransmission fluid temperature sensor
Electronic controlled automatic transmission, ECTElectronically controlled automatic
Intermediate shaft speed sensor ºAºCounter gear speed sensor

EC087±03
± EMISSION CONTROLEMISSION CONTROL SYSTEM
EC±1
2709 Author: Date:
2005 SEQUOIA (RM1146U)
EMISSION CONTROL SYSTEM
PURPOSE
The emission control systems are installed to reduce the amount of HC, CO and NOx exhausted from the
engine ((3) and (4)), to prevent the atmospheric release of blow±by gas±containing HC (1) and evaporated
fuel containing HC being released from the fuel tank (2).
The function of each system is shown in these table:
SystemAbbreviationFunction
(1) Positive Crankcase Ventilation
(2) Evaporative Emission Control
(3) Three±Way Catalytic Converter
(4) Sequential Multiport Fuel Injection*PCV
EVAP
TWC
SFIReduces HC
Reduces evaporated HC
Reduces HC, CO and NOx
Injects a precisely timed, optimum amount of fuel for reduced exhaust
emissions
Remark: * For inspection and repair of the SFI system, refer to the SF section in this manual.

EC0JM±02
EC±14± EMISSION CONTROLTHREE±WAY CATALYTIC CONVERTER (TWC)
SYSTEM
2722 Author: Date:
2005 SEQUOIA (RM1146U)
THREE±WAY CATALYTIC CONVERTER (TWC) SYSTEM
ON±VEHICLE INSPECTION
1. CHECK EXHAUST PIPE ASSEMBLY
(a) Check the connections for looseness or damage.
(b) Check the clamps for weakness, cracks or damage.
2. INSPECT TWC
Check for dents or damage.
If any part of protector is damaged or dented to the extent that it contacts the TWC, repair or replace it.
3. INSPECT HEAT INSULATOR
(a) Check the heat insulator for damage.
(b) Check for adequate clearance between the TWC and heat insulator.