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
3,025

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.
Mechchic
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

  • 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

  • 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

  • 08 Gran prix 3.8, p0402 & p0420 2 answers

    2008 Pontiac Grand Prix Base

    -

    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 3,872 nationwide Grand Prix listings starting at $1,490.
ZIP:

Search Pontiac Grand Prix Questions

Pontiac Grand Prix Experts

#1 Js08016
Js08016
Reputation 2,010
#2 Tom Demyan
Tom Demyan
Reputation 1,640
#3 John Saffrahn
John Saffrahn
Reputation 1,090
View All

Related Models For Sale

Used Chevrolet Impala"
1,403 Great Deals out of 58,465 listings starting at $1,700
Used Pontiac Grand Am"
37 Great Deals out of 1,896 listings starting at $1,200
Used Chevrolet Monte Carlo"
34 Great Deals out of 1,763 listings starting at $1,599
Used Pontiac Bonneville"
15 Great Deals out of 725 listings starting at $1,988
Used Chevrolet Malibu"
1,095 Great Deals out of 59,703 listings starting at $799
Used Chevrolet Camaro"
404 Great Deals out of 34,322 listings starting at $1,950
Used Nissan Altima"
1,389 Great Deals out of 85,027 listings starting at $1,495
Used Ford Mustang"
525 Great Deals out of 35,144 listings starting at $1,600
Used Pontiac GTO"
7 Great Deals out of 280 listings starting at $7,988
Used Nissan Maxima"
454 Great Deals out of 14,004 listings starting at $1,800
Used Chevrolet Tahoe"
759 Great Deals out of 23,760 listings starting at $1,950
Used Honda Accord"
1,186 Great Deals out of 61,913 listings starting at $900