filled up gas tank and p0420 code came on

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

Question type: Maintenance & Repair

2 Answers

4,525

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.

2 out of 2 people think this is helpful.
10

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.

1 out of 1 people think this is helpful.

Your Answer

Add photo

Related Questions

  • what makes the gas pump nozzle keep shutting off when filling my tank on my 2007 gxp 2 answers

    2007 Pontiac Grand Prix GXP with trouble code 446, and hard to fill tank without the pump nozzle from shutting off repeatedly.

    2007 Pontiac Grand Prix GXP

    -

    Maintenance & Repair

  • 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

  • Getting a code P0442 and P0442 pd after my car stalled out going down the road and had to tow it home. 2 answers

    Not sure if it matters, but we just put new exhaust on and replaced both CV shafts. After we got it all fixed it ran fine, I filled up car (first time totally filling it since I bought it, was only s...

    1999 Pontiac Grand Prix 4 Dr GTP Supercharged Sedan

    -

    Maintenance & Repair

  • 2006 pontiac Grand Prix GXP code: P1811 1 answer

    Put gas n car, drove it 10miles then it started cutting out(buckling), put sea foam treatment n it and HEET but Did not help. Couple days later the transmission started slipping. Ran the gas out ...

    2006 Pontiac Grand Prix GXP

    -

    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 2,896 nationwide Grand Prix listings starting at $879.

ZIP:

Search Pontiac Grand Prix Questions

Pontiac Grand Prix Experts

#1 Js08016
Js08016
Reputation 4,070
#2 Tom Demyan
Tom Demyan
Reputation 2,710
#3 munron
munron
Reputation 2,110
View All

Related Models For Sale

Used Chevrolet Impala
595 Great Deals out of 29,130 listings starting at $1,300
Used Pontiac Bonneville
522 listings starting at $1,695
Used Chevrolet Monte Carlo
10 Great Deals out of 1,413 listings starting at $2,500
Used Chevrolet Malibu
812 Great Deals out of 88,732 listings starting at $1,900
Used Pontiac Grand Am
1,309 listings starting at $799
Used Chevrolet Camaro
144 Great Deals out of 35,537 listings starting at $1,995
Used Ford Mustang
317 Great Deals out of 45,660 listings starting at $2,000
Used Pontiac GTO
5 Great Deals out of 434 listings starting at $5,995
Used Nissan Maxima
276 Great Deals out of 26,135 listings starting at $2,545
Used Pontiac Firebird
9 Great Deals out of 791 listings starting at $1,800
Used Nissan Altima
810 Great Deals out of 78,278 listings starting at $470

Used Cars For Sale

2008 Pontiac Grand Prix For Sale
10 Great Deals out of 430 listings starting at $2,495
2007 Pontiac Grand Prix For Sale
5 Great Deals out of 427 listings starting at $1,200
2006 Pontiac Grand Prix For Sale
4 Great Deals out of 445 listings starting at $1,999
2005 Pontiac Grand Prix For Sale
353 listings starting at $2,999