P0300 GMC - Cylinder Misfire Detected Random Cylinders

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3  What does this mean?

Possible causes

  • Faulty spark plug (s)
  • Faulty ignition coil (s)
  • Clogged or faulty fuel injector (s)
  • Intake air leak
  • Fuel injectors harness is open or shorted
  • Fuel Injectors circuit poor electrical connection
  • Ignition coils harness is open or shorted
  • Ignition coils circuit poor electrical connection
  • Insufficient cylinders compression
  • Incorrect fuel pressure

Tech notes

The P0300 code means that a cylinder(s) is misfiring or is randomly misfiring. Start by checking for intake leaks, intake gaskets are a common caused of multi-cylinder misfiring. If no leak is found the next step is to replace the spark plugs. If the problem persists more tests needs to be done to diagnose the problem, see "Possible Causes".

There are factory service bulletins for the following GMC models:

2000-2008 GMC Sonoma
2000-2008 GMC Sierra
2000-2008 GMC Yukon
2000-2008 GMC Yukon XL
2001-2008 GMC Denali
2001-2008 GMC Denali XL
2001-2008 GMC Savana
2002-2008 GMC Envoy
2002-2008 GMC Safari
2002-2008 GMC Jimmy
2000-2008 GMC Factory Service Bulletin OBDII Code P0300

2014 GMC Sierra 1500
2015-2016 GMC Sierra, Yukon, Yukon XL
GMC Factory Service Bulletin OBDII Code P0300





User Submitted Video

When is the code detected?

The control module monitors the crankshaft speed and has detected a misfire condition

Possible symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Lack/loss of power
  • Hard start
  • Engine hesitation

P0300 Gmc Description

When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the Crankshaft Position (CKP) sensor signal to vary, the Engine Control Module (ECM) can determine that a misfire is occurring.
OBDII Code P0300 Gmc - Cylinder Misfire Detected Random Cylinders - Engine-Codes.com

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