Check engine light

10

Asked by Kittykatmac1 Oct 20, 2019 at 10:08 PM about the 2004 Pontiac Grand Prix GTP

Question type: Maintenance & Repair

Hello, I have a 2004 Pontiac Grand Prix and
whenever we go on the highway and it hits
over 75 the check engine light comes on
(second time happening) it never happens
under that or anytime. We took it to orileys to
get a free reading and it was reading too
much air in the 02 sensor well we started off
basic and went with air filter and then the
mass air flow sensor and it still goes off. But I
heard from my step dad that gm made shit 3.8
liter motors and that there is miss firing when
it gets up to that speed that’s why the light
goes on and to replace coils packs first ?

4 Answers

10

Our highway speed limit is 75 don’t think that’s a option for me to slow down because that can cause a reck.

1 people found this helpful.
26,865

Apologies. Max anywhere close to me is 70. You might try spark plugs first and then coil packs (and wires if so equipped).

1 people found this helpful.
18,715

First off ignore your step dad, he clearly doesn't know how to help you. Second, if the car's computer says to deal with an O2 sensor, then deal with an O2 sensor. Don't go off and randomly start replacing things that are unrelated to the problem. The auto industry didn't spend millions developing those self diagnostic systems for their cars because they had nothing else to do. O2 sensors fail all the time. I have 4 cars and 3 of them need O2 sensors or are at least giving me O2 sensor warning lights for various reasons. The good news the car will run just fine with a bad O2 sensor although it gets poorer gas mileage. If you have to pass an inspection (which I don't) you will need to fix it, other wise just keep on driving until you have the time, money, or inclination to deal with it. But don't just randomly start replacing part hoping the problem will magically go away. The only thing that's going to go away is your bank account.

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