CEL O2 Sensor Code

[subrvan]

Hi there group! New member and first post. I have a 94 EJ22 installed in my VW Vanagon and it is running fine although I get an intermittent CEL that indicates a bad O2 sensor. I replaced the sensor with a Bosch unit and CEL came back with same code. The CEL generally comes on when I am at a steady speed and will go off when I come to a stop or during acceleration. Any ideas? I did have an issue with an injector a couple years ago that I resloved with some cleaning; could an injector problem cause an O2 code?

Thanks!
Subrvan

[Legacy777]

Welcome to the BBS.

Most likely the reason you see the CEL when at steady speed is because the ECU is in closed loop operation and is wanting input from the O2 sensor. Once you stop or are at varying engine speed & load the ECU may not be in closed loop.

When you replaced the O2 sensor with a Bosch unit, was it a new sensor with the proper electrical connector, or was it one of those you have to connect to the existing electrical connector?

If it had the electrical connector and all you did was plug it in I would kind of guess the wiring from the O2 sensor to the ECU may be questionable. This diagram gives the basic layout of the wiring. I would suggest checking the resistance of the sensor circuit from the ECU plug to the O2 sensor plug at the engine.

http://www.main.experiencetherave.com/s ... r_diag.pdf

[subrvan]

Josh,

I appreciate the advice and the diagram!

Craig

[Legacy777]

You're welcome.

Let us know what you find out.