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

asked by on October 11, 2016

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.

Engine is misfiring Inspection $94.99 - $114.99 Get a Quote

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.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $70/hr

What others are asking

Gas gauge not working properly.
I would have a technician check the codes on the computer (https://www.yourmechanic.com/services/check-engine-light-is-on-inspection). It may help find the problem your having. The gas gauge not working could be the sending unit in the tank or the wiring going to the gauge....
Belts squealing
Hello. There is a specific procedure for setting the ignition timing. Once you are ready to check the timing, it is very simple to adjust it to specification. This should be done if it is 10 degrees off. Engine performance...
Gas smell
Hi. There was a recall back in 2012 for over 40,000 GM vehicles with a potential fuel leak. The source of the leak is a cracked port on the fuel pump module. There have been confirmed failures of the module...
Loud bang and shaking starting car
Hello. It sounds like there is a broken engine mount (https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-engine-mount) or transmission mount that may be causing the banging noise that you are hearing. It is possible that something was damaged in the suspension system (https://www.yourmechanic.com/article/what-components-of-the-suspension-or-steering-systems-are-prone-to-fail) which could also...
dash and console lights out - 2005 Chevy Cobalt
Try to adjust the dashboard light's rheostat to see if it is turned all the way dim in such a way that you cannot see the lights. If the rheostat is turned up and it the lights are still not...
Alignment - 2007 Lincoln MKX
For an alignment (https://www.yourmechanic.com/article/how-to-know-if-you-need-a-wheel-alignment-by-robert-tomashek) to be as precise as possible, the used tires (https://www.yourmechanic.com/article/how-to-know-when-to-replace-tires_2) on the car have to have reasonably uniform wear. The best alignment results will be obtained with new tires, but so long as the tires that...
My Bmw will not crank or start.
Hi there: It is very possible that the battery might be fully charged, but be lacking cold cranking amps. As a battery ages, the cells inside will begin to wear out, causing a reduction in the amount of 'cold cranking...
Throttle body needs to be replaced
Hello, thank you for writing in. It is difficult to say if the vehicle is safe to drive. If the vehicle performs well enough that you can drive it short distances, then you can continue to work with it within...
Car wont start or crank
You need to verify the shift cable has not come off the transmission causing the car to not be in park so it can start. If this is okay then you may have a theft system problem if light is...

Related articles

A Buyer’s Guide to the 2012 BMW 335d
Of Of all of the BMW 3-Series models available in this model year, the 2012 BMW 335d is one of the most powerful and subtlest on the road. This 4-dour sedan may look mild-mannered enough, but under the hood it’s...
P0105 OBD-II Trouble Code: Manifold Air Pressure (MAP) Barometric Pressure Sensor Electrical Circuit Problem
P0105 P0105 Trouble code definition Manifold Air Pressure (MAP) Barometric Pressure Sensor Electrical Circuit Problem What the P0105 code means P0105 is the general code for a problem with the MAP circuit having an electrical failure or malfunction. The MAP...
P0423 OBD-II Trouble Code: Heated Catalyst Efficiency Below Threshold (Bank l)
P0423 P0423 code definition Heated Catalyst Efficiency Below Threshold (Bank l) What the P0423 code means P0423 is an OBD-II generic code that the engine control module (ECM) got input from the heated catalyst efficiency sensor for bank 1 that...