Skip the auto shop - Our mechanics make house calls

Q: P0301 code, steady misfire.

asked by on

Wife came home with the car having a steady missfire and check engine light on. Never had a problem with it before, been running great. After scanning it showed P0301 "first cylinder missfire." I have since changed the #1 coil pack and all 6 spark plugs without any change. I am 31 years old and none of my vehicles have been wrenched on by anyone other than me for 13 years, but this time I may have to take it to the dealer. Can I take out the fuel relay and crank the motor while the intake is off safely? How else can you determine if the #1 plug is getting spark?

My car has 100000 miles.
My car has an automatic transmission.

Hey there. In order to check the cylinder for spark you have to remove the coil and insert a spark tester into the coil after reconnecting it. Then you can check to see if it has spark. The injector will need to be checked with a noid light to see if it is getting injector pulse. If you are getting spark and injector pulse then you may have a clogged injector or low compression on the problem cylinder. The most common problem is a clogged injector. If you need assistance having this checked, a qualified professional from YourMechanic diagnose the misfire and follow through with proper repairs.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
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

Get a quote

What others are asking

Q: Is it worth fixing

Hi there, thanks for writing in about your 2000 Cadillac Escalade. If you overheated the engine until it died, then you may have damaged the engine internally on cylinder number 4. Your water pump is most likely the part leaking....

Q: VSA and engine lights both come on when I excelerate the car and it runs rough.

Hi there. The VSA (Vehicle Stability Assist) is on for an issue that deals with the engine load. Check the codes that are stored or pending in the ECM (computer) since the check engine light is on. The code should...

Q: Temperature gauge sits on cold always

This is a common issue on this generation of the Chevy Malibu. This could be any one of a few problems. This could be a result of a bad BCM (Body Control Module). This is a module in your car...

Related articles

P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.