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Re: Can you diagnose a cat with a temp reading
Posted to Technical Theory Forum on 2/4/2008 6 Replies

Hi Daryl,

I wouldn't bother with the temperature test. I have found it to be very mis-leading. Here's how I diagnose a P0420:

Check for TSBs/calibration updates. Check exhaust condition (modifications, damage, etc.). Check for fuel control.

If everything... Login to read more.

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