Therostat/Check Engine Light

1998 Volvo V70, 65k miles. Temperature gage acts like a stuck-open thermostat, operates in bottom 1/4 unless putting a load on the engine. With a load on the engine, such as climbing a hill, the gage will go up to 1/2 but as soon as you come down the other side the gage drops back to 1/4 very quickly. When this first happened the check engine light came on. I drove the car to my destination and back without problems. Could these two problems be related? I can't get to a service shop until next week. Any comments would be appreciated.
Reply to
Scott Sargent
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The temperature gauge is not linear. If the engine temperature is anywhere near normal, it stays in the center, just so customers don't get too exited about fluctuating engine temperatures. If it is reading abnormally, the temperature is a long way from optimum. The fuel ECU expects the engine to warm up in a fixed amount of time. If it doesn't, (as when the thermostat is stuck open) it sets a code regarding the engine temperature sensor, and turns on the check engine light. Most garages change the sensor and thermostat at this point to avoid comebacks, but 99.9% of the time, only the thermostat is needed.

Reply to
Mike F

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