Diagnostic Code: P1135
Decode: Malfunction Bank 1 Sensor 1 Air/Fuel Ratio Sensor Heater Circuit
When the ECM detects that there is a heated oxygen sensor heater circuit that has malfunctioned, it will send out a P1135 code.
Symptoms of this Code:
- The Check Engine light comes on
What the Techs Say:
Check the connections to the sensor to ensure that there is no open or short in the wiring.
A air/fuel sensor must reach an operating temperature of 1,200 degrees Fahrenheit in order to create a precise voltage signal. The quicker the air/fuel sensor can reach the temperature needed, the quicker it can start sending the correct information to the ECM.
The air/fuel sensor has an ECM controlled heater element built into it to get it to the proper temperature. The ECM uses signals from the engine coolant temperature and the load on the engine in order to determine how it will control the heater. Your Toyota’s ECM operates the heater element circuit using a control flow to the ground.
The voltage signal is monitored by the ECM, and the ECM makes comparisons of the state of the circuit in order to determine whether it is operating at factory specifications.
What Causes this Code?
- The air/fuel ratio sensor bank 1 sensor 1 may be faulty
- There may be an open harness or a short on the air/fuel sensor bank 1 sensor 1
- There may be a poor electrical connection in the circuit to the air/fuel sensor bank 1 sensor 1
- The ECM may be faulty
Check these systems and you will likely find your culprit. If you cannot perform proper diagnosis, or if you are having trouble pinpointing the cause, always consult a certified Toyota mechanic when seeking professional guidance.