2002 GMC Sonoma GMC Sonoma Code P0301

Tiny
SNCDOC
  • MEMBER
  • 2002 GMC SONOMA
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 23,000 MILES
About one every 4 to 5 months I get the code P0301, #1 cylinder misfire. It almost always sets when the truck is idling. The code clears after about 50 miles and then doesn't return for another 4-5 months. I've replaced the #1 spark plug with no change.

Also I read in the Shop Manual that this code is sometimes thrown for the automatic when it is traveling on a bumpy road and the crank shaft and cam shaft gets off. I do have a long bumpy driveway, but the code doesn't usually come as I'm driving down the drive. There is a slight misfire sound when it is idling.

Any clues as to where to look?

Doug Simmons
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Wednesday, March 11th, 2009 AT 12:02 PM

5 Replies

Tiny
OBXAUTOMEDIC
  • EXPERT
Hi Doug,

Well either you type the code I wrong or you looked up the wrong code not sure which but here is the Code Def for what you have listed.

P0130 Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 1)

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Wednesday, March 11th, 2009 AT 12:07 PM
Tiny
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The code should be P0301, #1 cylinder misfire.

Sorry for the confusion.
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Thursday, March 12th, 2009 AT 11:24 AM
Tiny
OBXAUTOMEDIC
  • EXPERT
Hey Doug,

Ok, have you tried changing the #1 plug wire with another plug to see if the code moves from the #1 cylinder?

Check fuel pressure and fuel regulator.
Check for Vacuum Leaks.
Check compression
check coil.

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Saturday, March 14th, 2009 AT 9:55 AM
Tiny
SERPENTRACER
  • MEMBER
Check the crank position sensor.
Notorious failing part on these trucks that causes the missfiring codes.

Does the plug have any white soot deposites? This would indicate a lean cylinder possibly caused by a dirty fuel injector.
(from personal experience)
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Saturday, March 14th, 2009 AT 3:37 PM
Tiny
SNCDOC
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I hadn't thought about the crank sensor. I'll definitely check that first.

The spark plug I took out looked normal, at least from my experience with normally functioning plugs. No soot, and just a slightly gray coating.

I'll try the crank sensor next since that is one of the easier things to check.
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Sunday, March 15th, 2009 AT 9:43 AM

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