CHEVY Coolant Temperature Sensor / Check Engine Light


Master Mechanic
Sep 6, 2020
Thought I’d post my results.

So like my Bonneville, which also had a leaking thermostat, my 1988 Caprice has a small leak now as well.

Both had the housing with the EGR vacuum plugs on them, but the Chevrolet has a coolant temperature sensor as well.

Because a replacement thermostat housing with the plugs and sensor, is twice the cost of what a normal one would be with only brass fittings- I decided to see how I could unplug the sensor, but have the check engine light remain off.

After some research, I discovered for LS engines a chart that shows resistance values for the sensor, and what ohms a healthy operating temp is determined to be.

Since I couldn’t find one for regular SBC’s, I decided to guess a range of what might work.

It became clear that between 600-1000 ohms was a good place to start, so I tried 1 kilo ohm- and the check engine light is back to off.

Now code 15 is still in the ECM, but so far the light hasn’t come back.


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