P0306 HUMMER Cylinder 6 Misfire Detected

Possible causes
– Faulty spark plug 6
– Clogged or faulty fuel injector 6
– Faulty ignition coil 6
– Fuel injector 6 harness is open or shorted
– Fuel injector 6 circuit poor electrical connection
– Ignition coil 6 harness is open or shorted
– Ignition coil 6 circuit poor electrical connection
– Insufficient cylinder 6 compression
– Incorrect fuel pressure
– Intake air leak
Tech notes
The P0306 code means that the cylinder 6 is misfiring or is randomly misfiring. Start by checking for intake leaks an if no leaks are found the next step is to replace the spark plugs on cylinder 6. If the problem persist more tests needs to be done to diagnose problem, see “Possible Causes”
When is the code detected?
Engine Cylinder 6 is Misfiring.
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
– Lack/loss of power
– Hard start
– Engine hesitation
P0306 HUMMER 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.
HUMMER Technical Service Bulletins for P0306 code
2008 HUMMER HUMMER H3 ENGINE AND ENGINE COOLING:ENGINE
2009 HUMMER H3T ENGINE AND ENGINE COOLING:ENGINE
2009 HUMMER HUMMER H3 ENGINE AND ENGINE COOLING:ENGINE