codes p0300 and p0200

billywhoa · April 26, 2005

have been to the dealer 3 times for service engine light.

for codes p0300 and p0200 and p0442.

service done. can you tell me if any of these services are related to the codes.

1st- flushed injectors, throttle body cleaning, gas additive, gas filter and air filter

2nd visit- replaced intake manifold

3rd visit- run engine with top engine cleaner and vent solenoid and bracket

problem still exist. service engine light came back on 2 days later after last visit on the way down south 400 miles after service. engine felt like it was running on half a engine when driving at low rpms. (in traffic) on 1/4 tank. pulled over filled tank up and got back on highway. got out of traffic and engine light would start flashing again between 60-80mph. after an hour of driving at same speed light stopped flashing and was steady but car was running better. next mornin on the way to dealer light cut off complety no signs. dealer said fuel injection control unit code came up and then misfire code came up. any ideas what to check.

GM-Tech · April 26, 2005

Year? Model? Engine?

P0200 is an injector circuit fault, which could certainly result in the P0300. I would want to see the misfire history counts to narrow it down a little bit as to which cylinder is at fault. If it'd misfire with the scanner connected, that'd be a bonus. The P0200 is an electrical failure that no amount of injector cleaning will fix.

The P0442 is a small leak detected in the supply side (tank, cap, evap hoses, etc.) and is unrelated to the other two DTC's.

The flashing service engine soon light means STOP NOW. Continuing to drive with the light flashing can result in toasting the catalytic converter.

billywhoa · April 26, 2005

2002 denali 6.0

i could tell you it started in the winter. when it was below 32 degrees the engine would run really rough with a steady ses light. occasionally flashing. sometimes it would cut off. seems like when temp ambient temp was above 32f it would run fine. after first service for ses light, steady light came back on the same night when the temp reached below or around 32 that night. brought it back and then they changed the intake manifold, which kinda of made sense because car was in accident and i remember where the top screw for vortex plastic cover plate sits was slightly cracked. may have been a leak. but problem still exist and now it has happened regardless of outdoor temp. light has been off since saturday. drove from south carolina to ny no problem yet. but im sure its just waiting.

if circuit is at fault would that be a wire inspection from injector to injector. or continuity test.

thanks for help

and by the way the p0200 code i am just finding out about. the dealer only told me about the misfire code which i think is a result of something else which they didnt tell me. just found out about the p0200 code at another dealer in south carolina . got a diagnostic.

GM-Tech · April 26, 2005

p0200 could be a wiring problem, an individual injector problem, or even the PCM itself (though unlikely). If the issue doesn't exist at the time you're checking the various components, you're probably just going to be guessing.