Inspection Procedure

WARNING: This page is about a different variant/trim than selected.

HINT:

Read freeze frame data using the intelligent tester. Freeze frame data records 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.
A low A/F sensor voltage could be caused by a rich air-fuel mixture. Check for conditions that would cause the engine to run rich.
A high A/F sensor voltage could be caused by a lean air-fuel mixture. Check for conditions that would cause the engine to run lean.

CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0171, P0172, P0174 OR P0175)

Connect the intelligent tester to the DLC3.
Turn the ignition switch ON and turn the tester ON.
Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
Read DTCs.

Result

RESULT CHART

Display (DTC Output)	Proceed to
P0171, P0172, P0174 or P0175	A
P0171, P0172, P0174 or P0175 and other DTCs	B

HINT:

If any DTCs other than P0171, P0172, P0174 or P0175 are output, troubleshoot those DTCs first.

B: GO TO DTC CHART

A: GO to Next Step

PERFORM ACTIVE TEST USING INTELLIGENT TESTER (A/F CONTROL)

Connect the intelligent tester to the DLC3.
Start the engine and turn the tester ON.
Warm up the engine at an engine speed of 2, 500 rpm for approximately 90 seconds.
On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
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).
Monitor the output voltages of A/F and HO2 sensors (AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2) displayed on the tester.

Result:

The A/F sensor reacts in accordance with increases and decreases in the fuel injection volume:

+25% = Rich output: Less than 3.0 V

-12.5% = Lean output:

More than 3.35 V

NOTE: The A/F sensor has an output delay of a few seconds and the HO2 sensor has a maximum output delay of approximately 20 seconds.

RESULT REFERENCE CHART

Case	A/F Sensor (Sensor 1) Output Voltage		HO2 Sensor (Sensor 2) Output Voltage		Main Suspected Trouble Area
1	Injection Volume +25% -12.5%	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Injection Volume +25% -12.5%	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	-
1	Output Voltage More than 3.35 V Less than 3.0 V	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Output Voltage More than 0.5 V Less than 0.4 V	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	-
2	Injection Volume +25% -12.5%	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Injection Volume +25% -12.5%	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	A/F sensor A/F sensor heater A/F sensor circuit
2	Output Voltage Almost no reaction	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Output Voltage More than 0.5 V Less than 0.4 V	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	A/F sensor A/F sensor heater A/F sensor circuit
3	Injection volume +25% -12.5%	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Injection Volume +25% -12.5%	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Extremely rich or lean actual air-fuel ratio Injector leakage or blockage Gas leakage from exhaust system Fuel pressure MAF meter ECT sensor Air induction system PCV hose connections
3	Output Voltage Almost no reaction	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Output Voltage Almost no reaction	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Following the A/F CONTROL procedure enables technicians to check and graph the voltage outputs of both the A/F and HO2 sensors.

To display the graph, select the following menu items on the tester: DIAGNOSIS / ENHANCED OBD II /ACTIVE TEST / A/F CONTROL / USER DATA /AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2; then press the YES button and then the ENTER button followed by the F4 button.

Result

RESULT CHART

Result	Proceed to
Case 1	C
Case 2	B
Case 3	A

B: GO to step 11

C: GO to step 15

A: GO to Next Step

READ VALUE USING INTELLIGENT TESTER (MAF)
1. Connect the intelligent tester to the DLC3.
2. Turn the ignition switch ON and turn the tester ON.
3. Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / MAF and COOLANT TEMP.
4. Allow the engine to idle until the COOLANT TEMP reaches 75°C (167°F) or more.
5. Read the MAF with the engine in an idling condition and at an engine speed of 2, 500 rpm.
Standard:

MAF while engine idling: Between 1 g/sec. and 3 g/ sec. (shift position: N; A/C: OFF).

MAF at engine speed of 2, 500 rpm: Between 2 g/ sec. and 6 g/sec. (shift position: N; A/C: OFF).

NG: REPLACE MASS AIR FLOW METER

OK: GO to Next Step
READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)
1. Connect the intelligent tester to the DLC3.
2. Turn the ignition switch ON and turn the tester ON.
3. Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / COOLANT TEMP.
4. Read the COOLANT TEMP twice, when the engine is both cold and warmed up.
Standard:

With cold engine: Same as ambient air temperature.

With warm engine: Between 75°C and 100°C (167°F and 212°F).

NG: REPLACE ENGINE COOLANT TEMPERATURE SENSOR

OK: GO to Next Step
CHECK PCV HOSE CONNECTIONS
1. Check for PCV hose connections.
OK: PCV hose is connected correctly and is not damaged.

NG: REPAIR OR REPLACE PCV HOSE

OK: GO to Next Step
CHECK AIR INDUCTION SYSTEM
1. Check the air induction system for vacuum leakage.
OK: No leakage from air induction system.

NG: REPAIR OR REPLACE AIR INDUCTION SYSTEM

OK: GO to Next Step
CHECK FOR SPARKS AND IGNITION (see INSPECTION PROCEDURE )
NG: REPAIR OR REPLACE IGNITION SYSTEM

OK: GO to Next Step
CHECK FOR EXHAUST GAS LEAK
1. Check for exhaust gas leakage.
OK: No gas leakage.

NG: REPAIR OR REPLACE EXHAUST SYSTEM

OK: GO to Next Step
CHECK FUEL PRESSURE
1. Check the fuel pressure (See ON-VEHICLE INSPECTION ).
Standard pressure: 304 to 343 kPa (3.1 to 3.5 kgf/cm ² , 44.1 to 49.7 psi)

NG: REPAIR OR REPLACE FUEL SYSTEM

OK: GO to Next Step
INSPECT FUEL INJECTOR (INJECTION AND VOLUME)
1. Check the injection volume (See INSPECTION ).
Standard injection volume: 45 to 58 cm ³ (2.9 to 3.5 cu. in.) per 15 seconds

NG: REPLACE FUEL INJECTOR

OK: GO to Next Step
INSPECT AIR-FUEL RATIO SENSOR (HEATER RESISTANCE) (see TYPICAL MALFUNCTION THRESHOLDS )
NG: REPLACE AIR-FUEL RATIO SENSOR

OK: GO to Next Step
INSPECT INTEGRATION RELAY (A/F RELAY) (see INSPECTION )
NG: REPLACE INTEGRATION RELAY

OK: GO to Next Step
CHECK WIRE HARNESS (A/F SENSOR - ECM) (see INSPECTION PROCEDURE )
NG: REPAIR OR REPLACE HARNESS AND CONNECTOR

OK: GO to Next Step
REPLACE AIR-FUEL RATIO SENSOR
PERFORM CONFIRMATION DRIVING PATTERN

Fig 1: Vehicle Speed Driving Pattern
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. Connect the intelligent tester to the DLC3.
2. Turn the ignition switch ON and turn the tester ON.
3. Clear DTCs (see DTC CHECK/CLEAR ).
4. Switch the ECM from normal mode to check mode using the tester (see CHECK MODE PROCEDURE ).
5. Start the engine and warm it up with all the accessories switched OFF.
6. Drive the vehicle at between 60 km/h and 120 km/h (38 mph and 75 mph) and at an engine speed of between 1, 400 rpm and 3, 200 rpm for 3 to 5 minutes.
HINT:

If the system is still malfunctioning, the MIL will be illuminated during step (f).

NOTE: If the conditions in this test are not strictly followed, no malfunction will be detected.

CHECK WHETHER DTC OUTPUT RECURS (DTC P0171, P0172, P0174 OR P0175)

On the intelligent tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
Read DTCs.

Result

RESULT CHART

Display (DTC Output)	Proceed to
No output	A
P0171, P0172, P0174 or P0175	B

B: GO to step 3

A: END