DTC P0300 Complete Bank Misfires - keywords fuel P0300 P0301 P0302 P0303 P0304 P0305 P0306 quality

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

The above vehicles may display complete even or odd bank misfires with or without setting the DTCs. This concern may be exhibited on a decelerate to stop, after a hard accelerate or after highway speed driving. The misfire typically clears quickly but is severe when it's occurring. The fuel trims on the effected side will change but all other parameters will look normal.

These concerns may result from poor fuel quality (water, contamination, etc.). The concern may not be high ethanol content so fuel tester J-44175 may not confirm the poor fuel quality. Also a visual inspection of a fuel sample taken from the fuel pressure test fitting may not display a concern. The vehicle will need to have the fuel system flushed and the fuel tank REMOVED and cleaned. A known good fuel will need to be installed in vehicle and then retested.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.