P1135

P1135 - A/F Sensor Heater Circuit Malfunction (BANK1 SENSOR1)

CIRCUIT DESCRIPTION
To obtain a high purification rate of the CO, HC and NOx components of the exhaust gas, a three-way catalytic converter is used. For the most efficient use of the three-way catalytic converter, the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric air-fuel ratio.

The A/F sensor has the characteristic that it provides output voltage* being approximately proportional to the existing air-fuel ratio. The A/F sensor output voltage* is used to provide feedback for the ECM to control the air-fuel ratio.

By the A/F sensor output, the ECM can determine the deviation amount from the stoichiometric air-fuel ratio and control the proper injection time immediately. If the A/F sensor is out of order, ECM is unable to perform the accurate air-fuel ratio control.

The A/F sensor is equipped with a heater which heats the zirconia element. The heater is controlled by the ECM. When the intake air volume is low (the temperature of the exhaust gas is low), the current flows to the heater to heat the sensor for the accurate oxygen concentration detection.

DTC Detecting Condition:

*: The voltage value changes at the inside of the ECM only.

HINT:
- After confirming DTC P0125, use the OBD II scan tool or hand-held tester to confirm output voltage of the A/F sensor from the CURRENT DATA.
- The ECM controls the voltage of the AF1A+, AF1A- and terminals of the ECM to the fixed voltage, therefore it is impossible to confirm the A/F sensor output voltage without the OBD II scan tool or hand-held tester.
- OBD II scan tool (excluding hand-held tester) displays the one fifth of the A/F sensor output voltage which is displayed on the hand-held tester.




CONFIRMATION DRIVING PATTERN
1. Switch the hand-held tester from the normal mode to the check mode. (*1)
2. Start the engine and let the engine idle for 100 seconds or more. (*2)
3. Drive the vehicle at 40 km/h (24 mph) or more for 20 seconds or more. (*3)
4. Let the engine idle for 20 seconds or more. (*4)
5. Repeat the procedure (*3) and (*4) three times. (*5)
6. Let the engine idle for 30 seconds. (*6)
7. Check the oxygen sensor output voltage.

HINT: If a malfunction exists, the check engine warning light comes on.

NOTE: If the conditions on this test are not strictly followed, the malfunction will not be detected.

WIRING DIAGRAM:

Step 1 - 3:

INSPECTION PROCEDURE

HINT: Read freeze frame data using the hand-held tester or OBD II scan tool, as freeze frame data records the engine conditions when the 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.