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Old 08-13-2007, 01:03 PM
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Re: Downstream O2 sensor?

Quote:
Originally Posted by TomB985
It's the 4.3L, Vin w, VCM, codes P0137, P0141, 91,000 miles

The codes indicate a heater problem and low voltage on Bank 1 sensor 2.
If this is a 4 02 sensor system. It would be the sensor in front of the cat.

The downstream behind the cat 02 sensor would be Bank 1 sensor 3.

I would check the 02 sensor heater circuit and wiring and if the wiring is ok I would replace the sensor.

The VCM checks all 4 02 sensors readings and if one is dropping out it can throw off fuel mix.
MT
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