Reader Question: I have a 1997 Ford Aspire. It is very cold in Kentucky right now. My check engine light came on tonight. I recently had an oil change and I recently checked the radiator coolant.
Would the cold weather cause the check engine light to come on (yellow)? The only other thing that I have noticed recently is that the heater takes forever to heat and the temperature gauge hardly goes up at all anymore.
I have been blaming those two things on the weather and the age of the car (the AC has about quit working as well but the vent system is still OK – not great, just OK)
Do you have any suggestions?
The outside temperature probably has nothing to do with the check engine light, but the fact that the temperature gauge hardly moves and the heater not being hot could mean something.
I would double check the coolant level inside the radiator, not just, what you see in the plastic overflow bottle on the side of the engine. If the coolant is FULL and green, I would probably want to replace the thermostat to see if that helps the gauge and heater issue.
Usually the coolant level or thermostat operation has no bearing on the YELLOW check engine light, but I would try to improve your heater operation and get the engine temperature up to the normal area.
An engine that does not reach normal 210 degree Fahrenheit temperatures tends to run richer, meaning using too much fuel than an engine that IS at 210 or so temperature. An engine that is running rich COULD set the check engine light on your dash.
The thermostat is cheap and easy to replace and would be a good idea to do as maintenance if you have not done so in the last 20,000 miles or so.
A restriction in your radiator, which does not allow the hot antifreeze to circulate through out the engine, can also cause lack of heat from your heater, low temperature gauge readings, engine overheating and in this case, might cause the engine to run rich. Thus, turn on the yellow check engine light.
Here is more information on check engine lights:
These are my best guesses without being there to run some tests.