Car won't start when hot

I have a 1999 Mazda Protege. As of last summer it started giving me problems with not wanting to start after I had driven it around town for a little while. (IE: to the grocery store, to the bank and then to my sister’s house. It wouldn’t give me the same problem if I just went to the grocery store and back home. It would start up fine and I’d be on my way. Only when I went somewhere and shut it off then repeated that a couple more times.) I took it to a mechanic who wholeheartedly believed it was the coil packs not allowing my car to function properly. So we replaced those and everything seemed on the up and up. (Keep in mind that this was towards the end of summer and the temperature was dropping.) The car was perfect all throughout the fall and winter, but now that the temperature outside is starting to rise again it’s beginning to do the same thing it did last summer. I don’t want to take it to another mechanic that’s going to have me dish out an extravagant amount of money again only for the problem to persist. So I figured I would make a post on this forum to see if anyone has had the same problem or if anyone knows anything that could lead to my car being fixed.

Thank you!

The Crank or Cam position sensors can fail due to heat.

^ usually, though, a crank or cam sensor would also cut out when the engine is running, after getting hot. Since the OP doesn’t say anything about the engine cutting out when running, that would point away from the sensor, I would think.

Cody, you need to find a good mechanic who will diagnose correctly and not just throw new parts on it. Find a recommended local mechanic in the “mechanics files” of this website.

This should not be hard to diagnose properly. A car that won’t start is usually missing either spark or fuel, basically, and it’s not that hard to figure out which is missing and why. Any mechanic who can’t figure this out isn’t really a mechanic.

Its definitely something electrical… The mechanic SHOULD HAVE been able to figure this out the first time round rather than guessing it was the coil pack…which it could have been. The charge to change the two coil packs on that engine should NOT have been much at all…Its an extremely simple task to do that service.

Anyway…like the guys said…this should be easy to figure out… Just get the vehicle hot enough to repeat the problem and then find out what is missing… Fuel or Spark…and then follow the trail of breadcrumbs to the culprit. Not that hard to do


@jesmed1 Here’s what happened to my mom’s friend’s car

Her car would randomly not start

here’s the pattern. Drive around, do chores, get everything warmed up. Park, go to church. Come out, and often it wouldn’t start

It was the crankshaft position sensor

No fault codes, ever

No stalling, just no start

It can happen

Not all bad crank sensors lead to stalling and no starts. Some just have one or the other

wouldn’t rule that crank sensor out just yet

Even though it wouldn’t fail every single time, it happened a few times every week

After I replaced the bad sensor . . . I tested it, and I can tell you 100% it was the problem . . . that car has never failed to start, and it’s been several months. We ask her about it, and no trouble

@db4690, thanks for that info. Didn’t know that.