2000 Toyota Avalon • 125,000 miles

I had some repair work done on the intake manifold of my 2000 Avalon with 125K miles. There was some oil leak from there. Now 1 week later the CEL comes on with codes P1135 and P1155. Figured that was Bank 2 Sensor 1 (front of engine exhaust manifold ) and Bank 1 Sensor 1 (rear engine exhaust manifold ) A/F sensor heaters going bad. Both heater circuit resistance was too high. Had them replaced by the local mechanic with OEM equiv. Denso 234-9021. Denso makes the actual Toyota sensors (with the Toyota labels).

After an hour the CEL is back with same P1135 and P1155. Mechanic says resistance is within range on both sensors. However he checked the wiring and the A/F Sensor Heater Relay and he is seeing +1 V higher. All fuses are OK. Wondering what to do now. Should I replace the Denso ones with the Toyota branded ones? Could the ECU be bad?
September 29, 2011.

You need a new tech that can track this down for you. I am glad to see he checked the fuses for the heater as one of the sensors had a bad heater. The chances of 2 failing at the same time are slim to none.
You need to see if the pcm is providing a ground for the heaters. If it is not, then it may be a pcm. If it does, then it may need different sensors. We use only oem air/fuel ratio sensors.


Sep 29, 2011.
On my 2000 Toyota Avalon I had codes P1135 and P1155 AF heater malfunction. I replaced both AF sensors, mass air flow sensor, throttle position sensor, sparkplugs, and sent PCM in for repair. PCM had some bad components related to the o2 portion. Still had light on after all this. Reading that the heater circuit is grounded through the PCM I ran a ground wire from the PCM to the battery and light went out. Problem solved.

Hot Wheels
Aug 8, 2015.