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Old 12-28-2005, 04:30 PM
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Brian R. Brian R. is offline
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Re: CEL- P0420 OBD 2 code

If you have access to an oscilloscope, ideally you should compare the waveforms of the two HO2 sensors, before and after the CatConverter. This will tell you if the CatConverter is bad and if the problem lies with the HO2 sensor.

The only test for the HO2 sensor by itself is measuring the resistance between terminals +B and HT of the sensor. Resistance should be 11-16 ohms cold and 23-32 ohms at operating temperature.

If I were you, I would bring it to someone with an oscilloscope to avoid wasting money.
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