Check engine light
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 ?