What causes the check enlight to come on and show error code P0420? What do you have to do to repair it?
Dec 1, 2009 at 10:19 PM
Repair Safety Notice:
This information is for general instructional purposes only. Vehicle repair can be dangerous.
Verify all information, follow manufacturer service procedures, use proper tools and safety equipment,
and consult a qualified repair shop when needed.
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BLUELIGHTNIN6
CAR REPAIR CONTRIBUTOR
16,542 POSTS
DTC P0420 indicates Catalyst Sensor 1 / Bank 1 Efficiency Failure. Normally caused by faulty or failing oxygen sensor. Nothing serious at all, most it will do is cause your fuel mileage to drop slightly.