[align=left]We've had issues with our check engine light ever since we got our Mazda 3 (which is a 2004). We've brought it in twice, while it was still under warranty and both times they told us they couldn't find anything wrong, they turned it off and sent us on our way, only for it to turn back on a few weeks later.

Well, you can only go through this so many times and we didn't want to bring it in again and pay $100 for someone to tell us nothing was wrong again, so we just left it on. Now we can't pass emissions here in CT because of it and we're going through this B/S again. We're being told we need a new thermostat and coolant sensor.

Has anyone been dealing with this as well? Is it really the thermostat and Coolant sensor, or is it a software thing that keeps making this thing go off? If anyone has dealt with this and figured out what was going on, information would be great!

Thanks!
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Do yourself a favor and actually pull the code yourself. Most autoparts stores will loan you a code reader that will tell you which code is being set to trip the Check Engine Light. CEL goes off for many reasons (even more on newer vehicle due to more stringent requirements from the gov't) For instance....not tightening your gas cap completely will set it off.

Is your car no longer under warranty? The dealer shouldn't charge you anything to figure out what the code is (or to fix it) if you are under warranty (4 years/50,000 miles to my knowledge......that is what the warranty on my 05 was.)

 

Without a code it is hard to say. You can disconnect the battery and step on the brake pedal to clear the codes then get your inspection. Autozone checks codes free.

 

P0126 Insufficient Coolant Temperature for Stable Operation, I know this was one of the codes...and there was one other, I think something about the thermostat...
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