filled up gas tank and p0420 code came on

jnsn
0

Asked by jnsn May 05, 2014 at 11:11 PM about the 2003 Pontiac Grand Prix SE

Question type: Maintenance & Repair

2 Answers

Norm Davis
2,065

P0420 code (Catalytic Converter) can be generated by any number of sensors upstream of the converter. More than likely there is a problem with the evap recovery system or the valve that's supposed to prevent over-filling the tank. When this happens, excess gas fumes are drawn into the engine (as it should) causing a rich condition, which triggers the Cat sensor to throw the P0420 code. Get the tank filler pipe and evap system checked out. There is probably one or more other codes being thrown, check the entire system.

Mechchic
0

You may just have a loose gas cap. When I worked in parts, I had that code and complaint all the time and 95% of the time it was cause of a loose gas cap.

Your Answer

Related Questions

  • Any suggestions for code P0420 & P1404 for a 3.8L? 2 answers

    Is an EGR Valve on a 3.8L difficult to clean or remove & replace? Most likely I will have to have a mechanic replace my Catalytic Converter. Is it best to purchase the Universal Catalytic Converter ...

    2002 Pontiac Grand Prix GT Coupe

    -

    Maintenance & Repair

  • car will start real rough chug and then die 9 answers

    its a 1996 grand prix special edition coupe 3100 v6 i drove it to the gas station put gas in it and about 3 miles down the road started running real rough and wanting to die i turned a corner and it c...

    Pontiac Grand Prix

    -

    Maintenance & Repair

  • evaporative fuel system leak 4 answers

    My 1998 grand prix GTP is throwing a code for evaporative fuel system leak. I have replaced the gas cap and the code went away for a while and came back. What else could be causing this condition?

    1998 Pontiac Grand Prix 2 Dr GT Coupe

    -

    Maintenance & Repair

  • Pontiac GP GTP Car turns over but wont stay on 15 answers

    I have had this problem before and the Mechanic told me it was a Position sensor. Then I took it for an oil change and came out and it was running ruff (turn the car on then it would fire you’d have...

    2002 Pontiac Grand Prix GTP

    -

    Maintenance & Repair

  • P0420 code 1 answer

    Code goes on for a week and off for a week, I took it to the shop and they said I had a bad gasket that connects the converter to the muffler,they fixed it but light is back on...help!!!

    2006 Pontiac Grand Prix

    -

    General

Grand Prix
Looking for a Used Grand Prix in your area?
CarGurus has 5,742 nationwide Grand Prix listings starting at $1,295.
ZIP:

Search Pontiac Grand Prix Questions

Pontiac Grand Prix Experts

#1 Js08016
Js08016
Reputation 1,480
#2 Tom Demyan
Tom Demyan
Reputation 1,170
#3 John Saffrahn
John Saffrahn
Reputation 770
View All