P0300 GMC 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
First diagnose P0300 GMC code
Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded terminals.
P0300 GMC Tech NotesThe 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
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Cost of diagnosing the P0300 GMC code
Labor: 1.0The cost of diagnosing the P0300 GMC code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.
When is the P0300 GMC code detected?The control module monitors the crankshaft speed and has detected a misfire condition
P0300 GMC Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Lack/loss of power
- Hard start
- Engine hesitation
P0300 GMC MeaningWhen 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.
P0300 GMC More InformationNeed more information on how to fix the P0300 GMC code?
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