Replaced temp sensor... Check engine for 2-3 minutes...
Thread Starter
7th Gear
Joined: Aug 2017
Posts: 7
Likes: 0
Replaced temp sensor... Check engine for 2-3 minutes...
I was having an intermittent problem with my temperature sensor. I'd get the occasional hard start problems. So I bought a new temperature sensor (the one in the front of the engine) and replaced it.
Now whenever I start my car cold, it hard starts and if I read the temperature off the dash it's stuck at 142 with the check engine lit up BUT only for about 2-3 minutes till the car warms up. Then it starts acting normal. If I turn off the car and restart, it's fine.
Looking around it seems like the 142 is a low voltage issue. The old sensor seemed to read fine most of the time but occasionally it did do the hard start which is why I replaced it. I don't know if I got a bad sensor but it seems odd that it would work after warming up.
Any advice is appreciated. Thanks!
Now whenever I start my car cold, it hard starts and if I read the temperature off the dash it's stuck at 142 with the check engine lit up BUT only for about 2-3 minutes till the car warms up. Then it starts acting normal. If I turn off the car and restart, it's fine.
Looking around it seems like the 142 is a low voltage issue. The old sensor seemed to read fine most of the time but occasionally it did do the hard start which is why I replaced it. I don't know if I got a bad sensor but it seems odd that it would work after warming up.
Any advice is appreciated. Thanks!
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
What year is the car?
The CTS (Coolant Temperature Sensor) on the front of the intake manifold (or on the water pump for LT1 engines) is used by the ECM. The CTS in the cylinder head (passenger side or driver's side, depending on year) is used by the dash to indicate coolant temperature. These two CTSs do not connect together in any way. If you have a '92 or later car, the digital temperature comes from the ECM. The analog temperature comes from the CTS in the cylinder head. That might be true for '90 and '91 also, I don't know for sure.
The CTS (Coolant Temperature Sensor) on the front of the intake manifold (or on the water pump for LT1 engines) is used by the ECM. The CTS in the cylinder head (passenger side or driver's side, depending on year) is used by the dash to indicate coolant temperature. These two CTSs do not connect together in any way. If you have a '92 or later car, the digital temperature comes from the ECM. The analog temperature comes from the CTS in the cylinder head. That might be true for '90 and '91 also, I don't know for sure.
Last edited by Cliff Harris; Sep 4, 2017 at 04:25 AM.
Thread Starter
7th Gear
Joined: Aug 2017
Posts: 7
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It's a 92.
Wrong part wouldn't surprise me, but it looked identical. Amazon claimed it was the right part but I wouldn't be surprised.
Would a wrong model part take a few minutes to warm up?
It was doing the hard start thing on occasion (that's why I replaced the sensor).
Wrong part wouldn't surprise me, but it looked identical. Amazon claimed it was the right part but I wouldn't be surprised.
Would a wrong model part take a few minutes to warm up?
It was doing the hard start thing on occasion (that's why I replaced the sensor).
Last edited by tsk; Sep 4, 2017 at 02:15 PM.
Zen Vet Master Level VII
Joined: Mar 2016
Posts: 5,214
Likes: 1,173
From: Southlake, TX
It sounds like you may have gotten the wrong part. The way I understand it the coolant sensor has a WAY larger read from -40 to +250ish, and is WAY more accurate than the gauge sensor, which will only move the needle on the cluster once it reads a certain temp, which in your case sounds like 142. Makes sense that your car runs funny until it warms up--- it thinks that it is 142 when stone cold.
Thread Starter
7th Gear
Joined: Aug 2017
Posts: 7
Likes: 0
Just to finish this with the solution: I went to my local auto parts store and got another sensor. The new sensor was identical to the old one (near as I can tell, the number stamped on the sensor was the same). I'm fairly certain the "original" sensor I put in was just defective. New one works like a champ.
Intermediate
Joined: Sep 2017
Posts: 27
Likes: 9
From: Dataw Island SC
If it's like mine (93 LT-1), the ECM sensor (water pump) connects with a 2 pin connector, the gauge sensor (RH cyl head) is a single pin. I replace my ECM sensor several times before getting a good one. Seems they are notorious for being bad out of the box. I finally got a good one from NAPA - NAPA boxing but can't remember the part number. Sensor failure will read 142 on the digital readout. Sounds like yours is not reading low temps but is reading higher. Still a bad sensor.
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Safety Car
Joined: Jan 2004
Posts: 4,549
Likes: 343
From: Glastonbury CT
Ohm meter
[QUOTE=B757captain;1595723770]If it's like mine (93 LT-1), the ECM sensor (water pump) connects with a 2 pin connector, the gauge sensor (RH cyl head) is a single pin. I replace my ECM sensor several times before getting a good one. Seems they are notorious for being bad out of the box. I finally got a good one from NAPA - NAPA boxing but can't remember the part number. Sensor failure will read 142 on the digital readout. Sounds like yours is not reading low temps but is reading higher. Still a bad sensor.[/QUOTE Boil some water and place sensor probe in it but do submerge two wire pin. Attach leads from meter and read resistance then record number. After water cools test again makeing sure the electrical connectors on sensor are not touching the resistance should be diffrent if not bad sensor