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Faulty Coolant Temp Sensor?

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Old 04-20-2017, 09:33 AM
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Default Faulty Coolant Temp Sensor?

Hey, everyone.

Lately, I've been having erratic coolant temperature readings on the gauge from time to time, where the needle would drift back and forth while the engine's working its way to full operating temp, where the engine's idling RPM becomes unsteady while this happens. In addition, the needle would less commonly jump upwards to as high as the third quarter mark all of a sudden, activating the radiator fans and then quickly falling back to the middle in less than a minute. So my question is, can a faulty coolant sensor in an LS1 erratically give higher than actual temperature readings or does the mechanism of the temp sensor's function necessarily confine it to give only lower than actual temperature readings when malfunctioning?

Can someone also tell me where the sensor's located?

Thanks very much.
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Old 04-20-2017, 12:12 PM
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It's above spark plug #1 in the cylinder head


Yes, I would replace that sensor. If your car is a 1998 it will require the specific 3 pin sensor
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Old 04-20-2017, 06:25 PM
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when you change it have the replacement real handy because coolant will start coming out as soon as you take it out...
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Old 04-21-2017, 11:27 AM
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Engine idle can be affected in some cars. My 1998 runs horrible with a failed or unplugged temp sensor. It idles so bad it backfires and wants to stall.

Thats why I keep a spare in my car.

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Old 04-23-2017, 10:49 PM
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Originally Posted by LS6427 View Post
Engine idle can be affected in some cars. My 1998 runs horrible with a failed or unplugged temp sensor. It idles so bad it backfires and wants to stall.

Thats why I keep a spare in my car.

.
Mine won't even crank if the temperature sensor is bad, or unplugged.
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Old 04-28-2017, 10:18 AM
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Originally Posted by Need4Camaro View Post
Mine won't even crank if the temperature sensor is bad, or unplugged.
I hear you.

I've been telling people for a long time....all PCMs are not the same. I have many friends who's cars run perfect without the coolant temp sensor plugged in or broken off with the sensor still in the head. Some run ok, some will run really really bad like mine.

And now yours.....won't even start.

Its all up to the PCM......

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Old 05-05-2017, 07:54 AM
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When mine was bad I had to disconnect it. It would run in limp mode and often be hard to start. Also the fans would run constantly even for a few minutes after the car turned off
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