P1135 Toyota

Diagnose and fix a P1135 Toyota trouble code

A P1135 Toyota trouble code is defined as A/F sensor heater circuit malfunction (Bank 1 Sensor 1). Air/fuel sensors don’t start providing data to the PCM until they reach a certain temperature. To speed up the heating and not rely solely on exhaust heat, the air/fuel sensor has a built in heater.

Causes of P1135 Toyota Rav 4 trouble code

We’ll use a 2002 Toyota RAV 4 in this example. Since this P1135 Toyota code refers to the heater circuit, that’s where you should start your diagnosis. The air/fuel sensor gets power from the air/fuel relay located in the engine compartment junction box. Plus, that circuit is fused by the A/F fuse. Begin diagnosing a P1135 problem by checking the A/F fuse. If it’s good, check for battery power coming out of the engine compartment junction box on the black/red wire, or check the black/red wire at the air/fuel sensor with key ON. If you see power on that wire, check for good ground on the white wire at the air/fuel sensor. If you see power and ground, you’ve confirmed that the problem is a bad air/fuel sensor.

Replace the air fuel sensor to fix the P1135 problem.

This is a screw in style air/fuel sensor. If it’s original, it’s probably a 7/8” hex. Start the engine and let it heat up for a bit before trying to remove the sensor. Then use a wrench or an oxygen sensor socket to remove the air/fuel sensor. The new sensor will come with a dab of anti-seize compound already in place. Don’t add more.