Q: My engine light is on, has increased emissions and reduced power, and car also shakes

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My car has shaken a lot since the engine light came on. I went to a mechanic and they diagnosed misfire on 7 of 10 cylinders. So they advised me to get tune up and change spark plugs so I did that. Still no change. After that I got another code saying misfire on cylinder 10 and delayed upstream o2 sensor. I drove it for one day then went back to Mechanic they read the codes again and it came up as misfire on cylinder 10 delayed o2 sensor and something about the coolant low on thermostat. They advised me that one problem was the misfire on cylinder 10, which they said was a bad coil so I let them swap the coil from cylinder 10 to another cylinder. I drove about 25 miles and the next day I took it to AutoZone they read my codes and now it says misfire on cylinder 10 and 3 and coolant thermostat (coolant temperature below thermostat regulating temperature). Please help.

Hello, thanks for writing in. The coolant temperature code can be due to low coolant or a failure in the thermostat. Most of the time this is a thermostat issue. As for the misfire problem, it is common for one or more coils to fail and cause this to occur. I usually test each coil to see if any of them are marginal. Many times on these vehicles just to prevent having continued issues with coils I change them all with the spark plugs if there are a lot of miles on the vehicle. I also do a compression test to make sure that the engine is fine internally. If there are multiple cylinders misfiring I also do a fuel pressure test because low pressure will cause this to occur. If you are looking to have your misfire and temperature codes looked at, consider YourMechanic, as a certified mechanic can come to your home or office to inspect this and make or suggest how to proceed with repairs.

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