Engine Light On - Obdii Fault Code P1155

[kammy1975]

Hi all, Need your help in ensuring I get the best diagnosis possible. My engine warning light is currently on, so took it to a friend who kindly read the code out. The machine stated P1155 A/F Sense Circuit Heater Malfunction(Bank2 Sensor1). There was also a History code of the exact same value, suggesting this problem has been there prior to my vehicle purchase. My friend cleared the code down, and when the engine was started, the code came back on immediately

I have read a lot of forums and posts on the internet, which talk about P1155 and P1135 fault codes, but wanted to ensure that my understanding of the problem was correct. I am aware that the sensor being referred to is found just to the left of the center of the manifold, and did the obvious by checking the state of the wiring, disconnecting the plug, giving it a clean, and plugging it back in. The fact that the light comes on immediately after a reset of the fault code suggests to me that there is an actual problem with the sensor, as I would expect the OBD to pick any other type of fault after a period of driving. Is this correct?

Is it possible to use a circuit tester to actual test the sensor? Have read that if there is a open circuit between the 2 black wires on the sensor, then the sensor is most likely faulty? Is this correct? I dont understand how the sensor works to know if this is a worthwhile check.

Finally does anyone know the actual part number of this unit, or a website that I can check Toyota part listings on ? Has anyone changed their sensor?

This is a RAV4.2 VVTI Petrol 1AZFE engine.

Thanks in advance for your responses.

[pmb]

Have a search on this forum , several posts about this. I have had two changed so far. The heater circuit goes open circuit instead of about 15 ohms. An American site oxygensensors.com has them listed. Usually 200 - 250 pounds from Mr T diagnosed and changed but on both occasions they didn't have one in stock. You can buy a tool with a cut out for the wires to change it and if it can't be removed without causing damage then more things may have to be replaced.