This Preliminary Information communication provides information to the technician about vehicles that have a Service Engine Soon Malfunction Indicator Lamp on. Technician will find Diagnostic Trouble Codes P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0351, P0352, P0353, P0354, P0355, and P0356. Technician will need to follow published Service Information diagnostics for the Diagnostic Trouble Codes first. The if Service Information diagnosis does not isolate the cause of this concern or if it leads to an ignition coil concern then mark the cylinder location on the top of all 6 ignition coils with a paint pen. Technician must check for Under hood Bussed Electrical Center connectors are properly seated, spark plugs for proper gap, cracks, carbon tracking, and corrosion, battery cables need clean and fully seated, and ground G115 to engine block - tight and clean on both sides of the ground cable. If the technician finds any of the conditions, make the necessary repairs then replace only the damaged coil, otherwise change all 6 ignition coils, all 6 spark plugs and the Engine Control Module. Technician will also inspect the related ignition coil fuse and replace it if open when here were misfires on one entire bank of the engine. Also check rear O2 performance to insure proper catalytic converter efficiency.
