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?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. P0301 code, steady misfire.

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: My car starts to misfire really rough after running it for about 30-60 minutes, shutting it off then starting it up

You have taken some great steps to try and resolve these issues. Looking to the spark system was a good choice. Plugs were a good start, but the distributor and wires may be causing the plugs to not receive the...

Q: Car is in limp mode. Low gears and reverse work however drive does not. Changed speed sensor and oil pressure sensor.

On many early 2000's Ford cars and SUV's, a shift control failure can trigger limp mode; however, this usually triggers an OBD-II code and illuminate the check engine light. Try downloading all codes to see if this is the issue....

Q: Service engine soon error message

If the check engine light is on (aka, "service engine soon"), that means that there is a malfunction in the engine, typically involving the engine controls such as ignition, fuel, air induction, emissions and so forth. There are thousands of...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
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.