Inspection Procedure

HINT:

• If DTC P0134 is displayed, check Bank 1 Sensor 1 circuit.
• If DTC P0154 is displayed, check Bank 2 Sensor 1 circuit.
• If the vehicle runs out of fuel, the air-fuel ratio is LEAN and DTCs P0134 and/or P0154 are recorded.

  The MIL then comes on.

• Read freeze frame data using OBD II scan tool or hand-held tester, as freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining 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. Are there any other codes (besides DTC P0134 and P0154) being output? 
   1. YES: Go to relevant DTC chart (See  DIAGNOSTIC TROUBLE CODE CHART  ). 
   2. NO: Go to next step. 
2. Check connection of PCV hose. 
   1. NG: Repair or replace PCV hose. 
   2. OK: Go to next step. 
3. Connect OBD II scan tool or hand-held tester, and read value for output voltage of A/F sensor. 

   PREPARATION: 

   1. Connect the OBD II scan tool or hand-held tester to the DLC3.
   2. Warm up the A/F sensor (bank 1 sensor 1) with the engine at 2,500 RPM for approximately 90 seconds

   CHECK: 

   1. Hand-held tester only:

      Select the "ENHANCED OBD2/SNAPSHOT/MANUAL SNAP SHOT/ALL/" mode on the hand-held tester.

   2. Read the voltage of A/F sensor (bank 1 sensor 1) on the screen of the OBD II scan tool or hand-held tester when performing all the following conditions.

   HINT:

   The voltage of AF1A+ (+) - E1 (-) terminals of ECM is fixed at 3.3 V and, and the voltage of terminals AF1A- (-) - E1 is fixed at 3.0 V.

   OK: 

   Normal condition: 

   Fig 1: Vehicle Condition Chart

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   Fig 2: Reading Voltage Of A/F Sensor At Stated Conditions

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   HINT:

   When the vehicle is driven:

   In the case that the output voltage of the A/F sensor is below 2.8 V (0.76 V)* during fuel enrichment (for example, when the vehicle tries to overtake another vehicle on a highway, the vehicle speed is suddenly increased with the accelerator pedal fully depressed), the A/F sensor are functioning normally.

   *: When using the OBD II scan tool (excluding hand-held tester).

   Malfunction condition: 

   Fig 3: Vehicle Condition Chart

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   Fig 4: Reading Voltage Of A/F Sensor At Stated Conditions

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   HINT:

   • Whenever the output voltage of the A/F sensor remains at approx. 3.3 V (0.660 V)* (see Fig 4) under any conditions 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 output voltage of the A/F sensor remains at a certain value of approx. 3.8 V (0.76 V)* or more, or 2.8 V (0.56 V)* or less (see Fig 4) under any conditions as well as the above conditions, the A/F sensor may have a short-circuit.

   *: When using the OBD II scan tool (excluding hand-held tester).

   1. OK: Go to Step   14 . 
   2. NG: Go to next step. 
4. Check for open and short in harness and connector between ECM and A/F sensor (See  PROCEDURE  ).  
   1. NG: Repair or replace harness or connector. 
   2. OK: Go to next step. 
5. Check resistance of A/F sensor heater (See  INSPECTION  ).  
   1. NG: Replace A/F sensor. 
   2. OK: Go to next step. 
6. Check air induction system (See  PRECAUTION  ).  
   1. NG: Repair or replace. 
   2. OK: Go to next step. 
7. Check fuel pressure (See  FUEL PUMP  ). 
   1. NG: Check and repair fuel pump, fuel pipe line and filter. 
   2. OK: Go to next step. 
8. Check injector injection (See  INSPECTION  ). 
   1. NG: Replace injector. 
   2. OK: Go to next step. 
9. Check gas leak on exhaust system. 
   1. NG: Repair or replace. 
   2. OK: Go to next step. 
10. Replace A/F sensor. 

    GO 

11. Perform confirmation driving pattern. 

    Go 

12. Are there DTCs P0134 and/or P0154 being output again? 
    1. YES: Check and replace ECM (See  PROCEDURE  ).  
    2. NO: Go to next step. 
13. Did vehicle run out of fuel in past? 
    1. NO: Check for intermittent problems (See  PRE-CHECK  ).  
    2. YES: DTCs P0134 and/or P0154 are caused by shortage of fuel. 
14. Perform confirmation driving pattern. 

    GO 

15. Are there DTCs P0134 and/or P0154 being output again? 
    1. NO: Go to Step   19 . 
    2. YES: Go to next step. 
16. Replace A/F sensor. 

    GO 

17. Perform confirmation driving pattern. 

    GO 

18. Are there DTCs P0134 and/or P0154 being output again? 
    1. YES: Check and replace ECM (See  PROCEDURE  ). 
    2. NO: Go to next step. 
19. Did vehicle runs out of fuel in the past? 
    1. NO: Check for intermittent problems (See  PRE-CHECK  ). 
    2. YES: DTCs P0134 and/or P0154 are caused by shortage of fuel.