03 dodge 1500 O2 sensor

Asked by Jun 27, 2017 at 03:52 PM about the 2003 Dodge Ram 1500 Laramie Quad Cab SB 4WD

Question type: Maintenance & Repair

My truck would load up on gas when you sit at an
idel for a little while. Had the check engine light ran
and it thrower code P0420. Changed the upstream
O2 sensor out and it ran great for about 3 days.
Now my light is back on it it's throwing the same
code. Is there something else that could be wrong
to make it read that?

3 Answers

845

Most likely needs a cat

The sensor is before the cat. With that still cause it to read wrong

845

There should. Be 2 sensors one before the cat and one after, the first one controls fuel and the second one checks the efficiency of the cat by compairing the reading of the upper one to the lower one, if the difference is out of limit it will throw the p0420 code for the cat efficiency

1 of 1 people found this helpful.

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