2002 Pontiac Grand Am Temp Sensor and Hard Starting

Trouble code says IAT sensor on 2002 Pontiac Grand Am GT 3.4L. Have replaced it twice with two brand new ones from different stores. Still showing problem code. Has problems with no start or hard start after sitting for a few hours. Runs fine when engine is warm. Could it be a broken or shorted wire in the IAT sensor circuit that just isn’t visible to the eye? Also, has harsh shifting problems too.

It sounds like you have multiple issues. As for the IAT sensor, I would only recommend replacing it with a GM part. Also check the wiring right at the connector for being broken, as that is quite common. You may have to bend it back and forth to show the break if there is one.

The last IAT sensor was an AC Delco. Runs fine when the car has been driven and only sits for a couple hours.

As for the hard starting, I’d check the fuel pressure regulator for leaks. The harsh shifting could be due to a number of things, and really should be checked out by a technician in person.

I thought that the harsh shifting etc might be the linkage?

There is no linkage other than the shift cable and that doesn’t cause that issue.

I thought maybe the starting problem might be something to do with moisture because if it has been running it stars right back up. My thinking…no moisture affecting it when running because they are heated up, but after sitting for a few hours there might be moisture get on a broken wire or something? Sound off?

Yeah, that really isn’t going to be your problem….let me explain why I think it may be the fuel pressure regulator. Starting cold, running for a while all is fine, even if it is leaking….after it sits, after being hot, that’s when the fuel regulator diaphragm leaks and gas gets into the intake system. Trying to start it then, usually is harder because it’s gotten too much fuel. Moisture is NOT going to be your problem even if you have a broken wire on the IAT.

Then what would a broken wire on an IAT do?

Cause the trouble code to come back. It’s NOT going to affect driveability. You’re putting your attention in the wrong place.

So if it is the FPR it would have no start or hard start when cold, but not when warm? Do I have that correct? Also, fuel consumption is awful now.

Either is a possibility depending on how bad it is leaking….and now that you mention fuel consumption is up, that has to be the problem. Replace it and be done!

Okay, so I will head to the dealer tomorrow to get the FPR and put that on and hopefully this will no longer leave my daughter stranded in the cold. Thank you so very much.

Great, have a nice night!

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