That is a code for the upstream heater on the O2 sensor. Usually indicates either a short or excessive resistance in the heater circuit. I would look over the harness real close for an area where it is rubbed through or damaged. It's possible it's an intermittent issue from a short. The heater wires are the two pink ones. One runs to the fuse for constant power. The other goes to the PCM 1 Connector on pin 3.
What the system does is monitor the battery voltage, then it compares that voltage to the voltage it sees from the O2 heater circuit. It knows the resistance of the heater in the sensor and the voltage drop it should cause. It sets the code if that voltage goes lower than expected through the higher resistance or a short.
To find the problem will take some testing. I would start the process with the meter. Go to the sensor and test the voltage feed to it from the fuse, make sure you have battery voltage.
Now go to the PCM and find pin 3 and the Pink wire. Use a T pin and back probe that connection. Connect the meter and look at the voltage returning from the sensor. Now go and wiggle and move the harness gently, look for the meter voltage to change or drop. Watch the harness as you do that and see if you can find the area that is causing the problem.
Thursday, June 16th, 2022 AT 12:41 AM