My service engine light keeps coming on.

10

Asked by Jan 27, 2014 at 12:42 AM about the 2002 Pontiac Grand Am GT Coupe

Question type: Maintenance & Repair

Been to 3 different service centers. Have replaced transmission, plugs, cables,cat converter, front oxygen sensor, tightened ground, air filter, oil change & filter. Today the security light came on when driving and all gauges when to zero even though I was driving 65 mph. Hate to keep spending money to fix the service engine problem.  Any ideas?

4 Answers

4,325

Service Engine light will come on for a variety of issues. Can you post the OBD trouble codes, someone might be able to point you in the right direction if we know what's triggering the service light. Pep Boys, AutoZone, and a few other chains will read the code for you for free.

10

P0420 is the code. It says the catalytic converter efficiency is low. Probable cause: cat converter defective (meineke says it isn't); engine misfire (I have new plugs and wires - unless the gaps weren't set properly); large vacuum leak (not sure how to tell); eng oil leak into exhaust-valve guide seals, piston rings. The two mechanics I've taken it to don't seem to think this is an issue. I won't go back to the dealer because they said the cause was the transmission. If you have any ideas of the cause and if there is a way I can look for signs before taking it to service, I'd appreciate it. Thanks.

4,325

Find the large vacuum leak. A vacuum leak will cause unmetered air to enter the engine, which causes a lean condition. The ECM will try to compensate by dumping additional fuel into the system, but you're actually running very lean. This will trigger the P0420 code and call up the "defective cat" code because the exhaust O2 sensors are reading the lean condition as a Cat issue. Meineke is probably right. I would also check the MAF sensor, make sure it isn't dirty. It can also throw a P0420 code. Once you've solved the vacuum leak, clear the code, and run the engine at 3000 rpm for a few minutes to blast out the Cat.

1 out of 1 people think this is helpful.
10

Thanks for the help.

1 out of 1 people think this is helpful.

Your Answer

Add photo

Related Questions

Grand Am

Looking for a Used Grand Am in your area?

CarGurus has 1,716 nationwide Grand Am listings starting at $1,995.

ZIP:

Search Pontiac Grand Am Questions

Pontiac Grand Am Experts

#1 tenspeed
tenspeed
Reputation 7,180
#2 John Saffrahn
John Saffrahn
Reputation 1,480
#3 Tom Demyan
Tom Demyan
Reputation 1,280
View All

Related Models For Sale

Used Pontiac Grand Prix
27 Great Deals out of 3,773 listings starting at $1,195
Used Pontiac Firebird
11 Great Deals out of 826 listings starting at $3,800
Used Ford Mustang
711 Great Deals out of 38,572 listings starting at $1,963
Used Chevrolet Impala
965 Great Deals out of 36,458 listings starting at $1,800
Used Chevrolet Monte Carlo
15 Great Deals out of 1,730 listings starting at $1,695
Used Chevrolet Malibu
1,124 Great Deals out of 79,772 listings starting at $2,495
Used Jeep Grand Cherokee
1,153 Great Deals out of 70,007 listings starting at $495
Used Chevrolet Camaro
666 Great Deals out of 39,407 listings starting at $3,495
Used Chevrolet Cavalier
1,364 listings starting at $1,000
Used Pontiac Bonneville
3 Great Deals out of 669 listings starting at $2,298
Used Ford Taurus
354 Great Deals out of 22,407 listings starting at $1,499
Used Ford Focus
1,232 Great Deals out of 59,542 listings starting at $1,395
Used Ford Explorer
1,491 Great Deals out of 72,941 listings starting at $985