When to take the Check Engine Light seriously


Nearly everyone who drives a car built since the mid-1990s has experienced the sinking feeling of the Check Engine Light (CEL) coming on and the frustration of trying to figure out what to do to make it go out.

This is a companion discussion topic for the original entry at https://www.hagerty.com/articles-videos/articles/2018/12/31/when-is-check-engine-light-serious


Just had a P045 on a 2006 Trailblazer - large evap leak. Did a bit of research, checked the evap surge valve by blowing into it and it did have a minor bit, I mean MINOR bit of air passing through, there should not be any air passing the valve when out of vehicle. New valve was $18.00 and once I figured out how to get my hand on the valve it took 20 minutes from start to end. Both a local shop and the dealer wanted over $600.


So, I had po401 on my 2012 Jetta. Pulled it up online and vw said it could be any of 12 issues including gas cap.

It ended up being the stupid gas cap…


Great article for someone thinking to take the leap into a “modern classic“ but worried about the mystery of the electronics. Great comments also, thanks.


We intermittently get a code on my wife’s Saturn Ion, relating to an exhaust O2 sensor. After some internet digging, it is a very common problem that can be summed up as “loose wire”. Basically, the harness connecting that O2 sensor is in a location that gets a lot of vibration. Secure that and the light goes out. Beats replacing the O2 sensor, because it’s usually welded into place, again due to it’s location and where it’s sensing.