Can a faulty thermostat diagnostic code be something besides the thermostat?

Asked by GuruDT2FXT Jul 15, 2024 at 01:38 PM about the 2003 Saturn L300 Base

Question type: Maintenance & Repair

The diagnostic code says I have a thermostat problem in my 2003 Saturn L300 still with low mileage, yet my temperature gauge is always low and the engine does not appear to overheat. Replacing the thermostat is complicated because of its location. Is it possible that there is some sort of faulty sensor instead?

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Gene answered 3 months ago

It could be a misreading sensor, live data scan can tell you that, but if the thermostat is stuck just slightly open and the computer sees that it is taking too long to reach a predetermined temperature, then it will set a thermostat code. My GM did this and it was the thermostat.

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James answered 3 months ago

Depending on which engine you have the engine must reach operating temperature of 180°F (2.2L) or 198° (3.0L) within ten minutes of a cold start up. If it doesn't the check engine light will come on and a trouble code will set. Since you said the temperature gauge is always low that points to a stuck open thermostat. Don't waste your money on parts you don't need. In the end it'll be cheaper to replace what's broken. In this case, the thermostat. Jim

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