Engine light is on, but not always.

JOEHERE

MEMBER
2007 CHEVROLET TRAILBLAZER
1.6L
6 CYL
2WD
AUTOMATIC
80,000 MILES

The engine light is normally on, sometimes it is off for a short while. When this first happened I took my
vehicle in to my dealer to check on it. It took several hours for them to determine that it was a dirty air filter.
That took care of it but I was disappointed because I always took my car to that dealer for all my service,
including all oil changes. It seems like they should have discovered the dirty filter a long time before this.
Since this was fixed, a few weeks later the light came back on. For a while it would come on and go back off
off in a few days. Now it is almost constant. I took it in and they looked at it for hours. Final, they said they
called Chevy and they recommended a $300 test to find out what was wrong. I said no for now, this was
at the Chevy dealer that I bought the vehicle at and always had serviced there. Suggestion?

1 Reply

CARADIODOC

MECHANIC
33,916 POSTS

Common story; same result.

The first thing is to find out exactly which diagnostic fault code is setting. The people at many auto parts stores will do that for you for free. The next is to find an independent repair shop. Eventually all GM owners do that. Look for a shop that has mechanics who specialize in engine performance problems. Knowing the fault code is just the starting point. That tells the mechanic which circuit or system needs further diagnosis. Those tests rarely take "several hours". Some codes do get pretty involved, and there are entire books that list all the test steps.

I doubt the air filter was the solution, but as far as your expectation they should have known it, that is unreasonable. Some air filters last a real long time and they're very difficult to get to, so they get ignored. When they DO get checked, a plugged air filter can easily appear to be just fine. You expect your mechanic to find things that haven't caused a problem yet, but we have the opposite problem. When we show an air filter to the car owner, they typically don't want to pay for a new one. They tell us they'll change it later, then we see it still in there at their next visit. We are commonly accused of trying to sell unneeded parts so we tend to not check for things like air filters.

These are just generalizations. If you list the exact fault code numbers, and provide some details, like what kind of test was recommended, I might be able to provide a better answer or suggest some steps to take.