Mitsubishi Repair: 95 Galant S - overheat/check engine, coolant temperature sensor, engine coolant temperature sensor

Question
Hey Anthony,

I have a couple issues with my car.

First lately my thermostat in the car has been quite unstable. One minute i am in the middle and next thing you know it is raising to the red, it never actually reaches the red before it begins to lower back to the center. It has me real worried since I just had a radiator flush not too long ago. Summer is coming and I would hate to deal with this then.

Secondly, my check engine light keeps coming on out of nowhere and then shutting back off. Its insane. One time all I did was put oil in and it turnd off. But now it is back on again ad I am not sure what else to do. I think it may have something to do with my fuel since I smell gas alot.

Answer
Anthony,
You should have your thermostat replaced.  Even if it was replaced during your last radiator flush, have it replaced again.  If it was new, it's possible it was defective.  I've seen the problem you described on several different cars, and it almost always turned out to be a bad thermostat.

But sometimes your coolant temperature can rise and cause your check engine light to come on due to a malfunctioning engine coolant temperature sensor.  If you smell excess fuel, that can be caused by a firing inconsistency from the spark plugs, malfunctiong emission component, failing oxygen sensor, or worn out catalytic converter.  If the check engine light comes and stays on, take it in to a mechanic to scan for trouble codes.  If you have an AutoZone in your area, many times they will check your car's computer for free.
Good luck!