Inspection Procedure
HINT:
Hand-held tester only:
It is possible the malfunctioning area can be found using the ACTIVE TEST A/F CONTROL operation. The A/F CONTROL operation can determine if the A/F sensor, heated oxygen sensor or other potential trouble areas are malfunctioning or not.
Perform the ACTIVE TEST A/F CONTROL operation.
HINT:
A/F CONTROL operation lowers the injection volume 12.5% or increases the injection volume 25%.
- Connect the hand-held tester to the DLC3 on the vehicle.
- Turn the ignition switch ON.
- Warm up the engine with the engine speed at 2,500 RPM for approximately 90 seconds.
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
- Perform the A/F CONTROL operation with the engine idle (press the right or left button).
Result:
A/F sensor reacts in synchronizing with increase and decrease of injection volume
+25 % --> rich output: Less than 3.0 V
-12.5 % --> lean output: More than 3.35 V
Heated oxygen sensor reacts in synchronizing with increase and decrease of injection volume
+25 % --> rich output: More than 0.55 V
-12.5 % --> lean output: Less than 0.4 V
The following A/F CONTROL procedure enables a technician to check and graph the voltage outputs of both the A/F sensor and the heated oxygen sensor.
For displaying the graph, enter "ACTIVE TEST / A/F CONTROL / USER DATA", select "AFS B1S1 and O2S B1S2" by pressing "YES" and push "ENTER". Then press "F4".
HINT:
- DTC P2A00 may be also detected, when the air fuel ratio is stuck rich or lean.
- 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.
- 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 determine 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.
- Are there any other codes (besides DTC P2A00) being output?
- YES Go to relevant DTC chart (see DIAGNOSTIC TROUBLE CODE CHART ).
- NO Go To Next Step
- Connect hand-held tester or OBD II scan tool, and read value for voltage output of A/F sensor.
PREPARATION:
- Connect the hand-held tester or the OBD II scan tool to the DLC 3.
- Warm up the A/F sensor (bank 1 sensor 1) with the engine at 2,500 RPM for approximately 90 seconds.
- Read the A/F sensor voltage on the hand-held tester or OBD II scan tool.
CHECK:
- Hand-held tester only:
On the hand-held tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II / SNAPSHOT / MANUAL SNAPSHOT / USER DATA. Read the values.
- Select "AFS B1 S1/ENGINE SPD" and press button "YES".
- Monitor the A/F sensor voltage carefully.
- Check the A/F sensor voltage under the condition as follows.
- Allow the engine to idle for 30 seconds.
- Engine is racing at approximately 2,500 RPM (when engine revolution is not suddenly changed).
- Raise the engine speed to 4,000 RPM and release the accelerator pedal fully quickly.
OK:
Standard:
Conditions (1) and (2)
Voltage changes a little in the vicinity of 3.3 V (0.66 V)* (between approximately 3.1 to 3.5 V) as shown.
Condition (3)
A/F ratio sensor voltage increases to 3.8 V (0.76 V)* or more during engine deceleration (when fuel cut) as shown.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
HINT:
- Whenever the A/F sensor output voltage remains at approximately 3.3 V (0.660 V)* (see "Malfunction Condition" graphic) under any condition as well as the above conditions, the A/F sensor may have an open-circuit. This will happen also when the A/F sensor heater has an open-circuit.
- Whenever the A/F sensor output voltage remains at a certain value of approximately 3.8 V (0.76 V)* or more, or 2.8 V (0.56 V)* or less (see "Malfunction Condition" graphic) under any condition as well as the above conditions, the A/F sensor may have a short-circuit.
- The ECM will stop fuel injection (fuel is cut) during engine deceleration. This will cause a LEAN condition and should result in a momentary increase in the A/F sensor output voltage.
- The ECM must establish a closed throttle position learned value to perform fuel cut. If the battery terminal has been disconnected, the vehicle must be driven over 16 km/h (10 mph) to allow the ECM to relearn the closed throttle position.
- When the vehicle is driven:
The output voltage of the A/F sensor may be below 2.8 V (0.76 V)* during fuel enrichment. For the vehicle, this translates to a sudden increase in speed with the accelerator pedal fully depressed when trying to overtake another vehicle. The A/F sensor is functioning normally.
- The A/F sensor is a current output element, and therefore the current is converted into voltage inside the ECM. If measuring voltage at connectors of the A/F sensor or ECM, you will observe a constant voltage.
*: Voltage when using the OBD II scan tool.
- OK: Go to step 17 .
- NG: Go To Next Step
- Check resistance of A/F sensor heater (see INSPECTION
).
- NG: Replace A/F sensor.
- OK: Go To Next Step
- Check EFI main relay.
PREPARATION:
Remove the EFI main relay from the engine room J/B.
CHECK:
Inspect the EFI main relay.
OK:
EFI MAIN RELAY TERMINALS RESISTANCETester Connection Specified Condition 3-5 10 kΩ or higher 3-5 Below 1 Ω (when battery voltage is applied to terminals 1 and 2) - NG: Replace EFI main relay.
- OK: Go To Next Step
- Check for open and short in wire harness between ECM and A/F sensor (see HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE
).
References: Bank 1 Sensor 1 System Drawing
- NG: Repair or replace harness and connector.
- OK: Go To Next Step
- Check air induction system (see SFI SYSTEM
).
CHECK:
Check for vacuum leaks in the air induction system.
- NG: Repair or replace.
- OK: Go To Next Step
- Check connection of PCV hose.
- NG: Repair or replace PCV hose.
- OK: Go To Next Step
- Check fuel pressure (see FUEL PUMP
).
CHECK:
Check fuel pressure (high or low fuel pressure)
- NG: Check and repair fuel pump, fuel pipe line and filter.
- OK: Go To Next Step
- Check injector injection (see
INSPECTION
).
CHECK:
Check injector injection (high or low fuel injection quantity or poor injection pattern).
- NG: Replace injector.
- OK: Go To Next Step
- Replace A/F sensor.
- Go: To Next Step
- Perform confirmation driving pattern (see DTC P2195, P2196: OXYGEN (A/F) SENSOR SIGNAL STUCK LEAN (BANK 1 SENSOR 1) & OXYGEN (A/F) SENSOR SIGNAL STUCK RICH (BANK 1 SENSOR 1)) .
HINT:
Clear all DTCs prior to performing the confirmation driving pattern.
- Go: To Next Step
- Is there DTC P2A00 being output again?
- YES Replace ECM (see ENGINE CONTROL MODULE (ECM) ) and perform confirmation driving pattern.
- NO Go To Next Step
- Confirm if vehicle has run out of fuel in past?
- NO Check for intermittent problems (see PRE-CHECK ).
- YES DTC P2A00 is caused by running out of fuel.
- Perform confirmation driving pattern (see DTC P2195, P2196: OXYGEN (A/F) SENSOR SIGNAL STUCK LEAN (BANK 1 SENSOR 1) & OXYGEN (A/F) SENSOR SIGNAL STUCK RICH (BANK 1 SENSOR 1)) .
HINT:
Clear all DTCs prior to performing the confirmation driving pattern.
- Go: To Next Step
- Is there DTC P2A00 being output again?
- NO Go to step 19 .
- YES Go To Next Step
- Replace A/F sensor.
- Go: To Next Step
- Perform confirmation driving pattern (see DTC P2195, P2196: OXYGEN (A/F) SENSOR SIGNAL STUCK LEAN (BANK 1 SENSOR 1) & OXYGEN (A/F) SENSOR SIGNAL STUCK RICH (BANK 1 SENSOR 1) ).
HINT:
Clear all DTCs prior to performing the confirmation driving pattern.
- Go: To Next Step
- Is there DTC P2A00 being output again?
- YES Replace ECM (see ENGINE CONTROL MODULE (ECM) ).
- NO Go To Next Step
- Confirm if vehicle has run out of fuel in past?
- NO Check for intermittent problems (see PRE-CHECK ).
- YES DTC P2A00 is caused by running out of fuel.