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In my experience, YES i have a 1996 GMC Yukon i started getting bad mileage like 10 in town 12.5 highway. Tried many things O2 sensor, a PCV valve, PCV line air leak, fuel and air filters. NO LUCK. Noticed thermostat was showing wild swings in temperature, thought maybe the gauge had gone bad, and i had replaced thermostat approx 4 years earlier, so thought thermostat can't be bad that quick. Long and short of it is I replaced thermostat it was bad and mileage immediately increased by 40%. Theory..... the computer thinks the car is running lean so it adds more gas. Don't let this happen to you i probably waste 500 dollars in fuel, for a 10 dollar part.
Scott N. Klamath Falls Or
Wiki User
∙ 12y ago
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Would a bad thermostat cause a decrease in gas mileage?
A bad thermostat can cause a decrease in gas mileage. If the thermostat is stuck open, the engine will tend to run cold. Not only will this result in a perpetually low temperature gauge reading and poorly performing heater. It will also cause the ECU to richen the mixture, since the engine will appear to be warming up to the ECU. This will result in poor gas mileage. Replacing the thermostat will allow the engine to fully warm up, which will restore gas mileage as well as heater performance.
Will incorrect tire inflation cause bad gas mileage?
bad gas mileage
Would a bad thermostat cause overheating in 1997 ford probe?
Yes a bad thermostat would cause overheating in any car. A thermostat regulates the temperature.
Can a bad MAF cause bad gas mileage?
Yes
Will bad O2 sensor cause bad gas mileage?
yes
Will a bad thermostat temp sensor cause a 1997 Plymouth grand voyager to overheat?
A bad thermostat can cause an overheat. A bad temp sensor can show an overheat when the temperature is normal.
Can a bad thermostat make ac blow hot air?
No. The thermostat is not likely to be the cause.
Will a bad thermostat cause your car to over heat?
Yes
Can a bad thermostat cause your home heat not to work?
Yes, it can.
Will a bad catylictic convertor cause bad gas mileage on a 99 accord?
Yes it certainly could cause bad gas mileage especially if it is plugged up or if your car's oxygen sensors readings are faulty.
Can a defective knock sensor cause bad mileage?
Yep.
Would a bad fuel pump cause a loss of gas mileage?
No, a bad fuel pump will cause a no run situation.
