Thread: Bad O2 sensor?
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Old 08-07-2006, 05:52 PM
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Re: Bad O2 sensor?

Quote:
Originally Posted by ErnieC
I have a 97 voyager 2.4 motor. I am getting bad gas milage. The check engine light is giving me code 21. I want to fix it myself. How do I know which O2 sensor is bad, the one in the manifold or the one by the cat?
Codes do not say replace sensors. They say check things out.
Code 21 can be 4 different problems on the downstream 02 sensor or wiring circuit.
Check all fuses to start with.
You will need the 4 digit P---- codes to know where to check.
Get a good scanner on it and read out data and codes and post back code no.
MT
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