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Q: Water gauge showing red hot, but engine is not hot.....is it a sensor if so which one?

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I changed my knock sensor plug because it was worn out. As I turned on the Supra to check if the engine light came off, I noticed that the water temp gauge was red hot, but that couldn't be possible because the engine was no where near hot. So I decided to change the thermo stat and the gauge continued to display red hot. Water pump is good, radiator is good, thermal stat is good, and I just changed thermal sensor about 6 months ago. My best guess is that at the time I changed the knock sensor plug, I might have bother a cable, but the knock sensor is no where near thermal state nor thermal sensor. If anyone knows the cable I might have bother please let me know. I'll be changing the thermal sensor and I hope that fixes it. Other that, anything else I can change please let me know. My supra is a 1986.5 3.0 Liters 6v

Thanks alot

Hi there. There are several coolant sensors for the supra; ac, fan, ecu, and gauge. It sounds like you may need the gauge sensor, but a wire harness or gauge issue could also be the culprit. This is a single wire sensor and may match the ac coolant sensor in the same vicinity. The two sensors have different colors on the top with the gauge usually having an orange or red color. It seems like the sensor has shorted internally and is causing the gauge to read improperly. I suggest having a qualified technician perform an inspection to determine if the sensor is faulty and avoid replacing unnecessary parts. Your Mechanic has several available technicians that can assist you with a temperature gauge is maxed out inspection.

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