Check Engine Light 07 mazda 3
 

Check Engine Light came on - local parts store checked the code.
2 possible problems -
Coolant low
Defective Engine Temp Sensor

I added more coolant - didn't think it was low but added some...not more than a cup.

56,000 miles

Any suggestions - local dealership sucks
Any suggestions?
Thinking about taking it and have diagnostics run just to make sure that the sensor isn't bad....

Thanks for the help!

My CEL came on so I took it to Advanced Auto Part where they hooked up the hand-held computer. They said is was the braking system. That's when I noticed a burnt out 3rd brake light.

Replaced the light, then all the brake lights quit working. I took them out and they checked good. A back to Advanced where the guy said the brake switch is probably bad, so I replaced the brake switch. Now the problem is intermittent. Sometimes the brake lights work, other times they don't. Regular lights and turning signals work fine.

I'm thinking there's a relay between my brake switch and brake lights somewhere, that's sticking or has an intermittent short. Anyone know where I can get a wiring diagram for a 2006 Mazda 3, 5 door hatchback? I've searched online, but most website take you to a sea of Google ads, with no mention the actual Mazda 3 wiring diagrams.

You can get a scan tool for under $100, and then you can see the code for yourself - and get what they call freeze frame data - which is the data that's live on the car communication bus. That would let you check if it's a bad temp sensor (if it reads way off from outside temp after sitting overnight). It will also show you a lot of other data on the car that you may find interesting or useful for future issues.