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Mastertech1
Mastertech1, ASE Master Technician
Category: Car
Satisfied Customers: 2261
Experience:  30 years of all phases automotive diagnostics and repair
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GETTING CODE P0300 ON A 2003 H2 HUMMER ONLY WHEN REV RPM ABOVE

Customer Question

GETTING CODE P0300 ON A 2003 H2 HUMMER ONLY WHEN REV RPM ABOVE 2500, WHILE IN PARK. NEED ADVISE.
Submitted: 7 years ago.
Category: Car
Expert:  Mastertech1 replied 7 years ago.
PO 300 code: misfire code as you probably know ! I see that you have replaced the spark-plugs,and the fuel filter.have you looked at the plug wires? some had coil over/some had wire to plug (which means it has short spark-plug wires)if yours has the wires then I would recomnend that you replace the wires. if not then then using a scanner . Try to break down which cyilinder it is po301 is cylinder #1 po302 is cylinder#2 and so on.I would rec. that that you replace the spark plug wires !These will show up more in higher rpms and under loads (going up hill or acc/ to pass, etc)

Edited by Autotech1 on 11/6/2009 at 6:30 AM EST
Customer: replied 7 years ago.
what about a diry egr valve.should i buy oem wires or 8mm, or 10mm wires? ther the short ones. under a load in passing gears revs above 2500 code light does not flash. only in park above 2500 rpm.then light stops flashing 30 seconds afer bring revs down.
Expert:  Mastertech1 replied 7 years ago.
I would rec.that you get the OEM eires (they are built to factory resistance)And yes a sticking egr valve can cause a multible engine missfire and code po300/or wires and when the light is flashing it is warning you that cat converter damage can happen

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