P000028 code and CEL keep coming back :(
10-12-2023, 10:33 AM
#1
P000028 code and CEL keep coming back :(
I've got a M177 engine 2019 GLC63 at 35000km. Recently I went to the shop and did an oil change, the second day "engine oil level too high" and the CEL was on. So few days after I went to the shop again and let some oil out, cleared the code. Then not long after the CEL came on again, checked the code was P000028, and it said "no more information could be provided" on the scanner. The shop cleared it multiple times and it kept coming back, It had been a month and the CEL had drove me crazy!!!
We did the following checks:
1. Cylinder 7 and 8 shows balance rate of +7 while the rest were normal (all negative small number).
2. The engine is a little bit rough but not noticeable, power seemed normal. (I noticed it when I put my hand on the driving wheel and can feel it shakes, similar to the feeling when the wheel's dynamic balance is messed up, so I am guessing a little bit misfire but not much)
3. ECO Start Stop did not work for a week but after I sent the car to the shop they said now it worked fine, aux battery was checked normal as well.
4. Oil was changed again but not the filter.
5. Plugs changed, coil switched, cable checked, smoke test done. My mech guy said they are all normal.
6. Fuel injector was left alone for now as my mech said no one in the area has dissembled a M177 engine before to change fuel injector, so they don't want to do that unless we know it's absolutely the injector causing problem. Plus I am guessing if that's the case, code would show and balance rate could be much bigger.
7. Dealer had the same fault code and they don't know why, updated the powertrain software, no ECM update available.
I read through the forum and notice there's misfire and fuel injector leakage with the M177, but I doubt that's the case here since there is only one fault code P000028, otherwise there would be multiple codes showing up.
I was guessing could be either the filter or the oil pressure sensor giving wrong signal so the engine oil level is wrong all along. But my mech said the oil pressure sensor is rarely faulty and no code is shown.
So what do you guys think is triggering the CEL?
We did the following checks:
1. Cylinder 7 and 8 shows balance rate of +7 while the rest were normal (all negative small number).
2. The engine is a little bit rough but not noticeable, power seemed normal. (I noticed it when I put my hand on the driving wheel and can feel it shakes, similar to the feeling when the wheel's dynamic balance is messed up, so I am guessing a little bit misfire but not much)
3. ECO Start Stop did not work for a week but after I sent the car to the shop they said now it worked fine, aux battery was checked normal as well.
4. Oil was changed again but not the filter.
5. Plugs changed, coil switched, cable checked, smoke test done. My mech guy said they are all normal.
6. Fuel injector was left alone for now as my mech said no one in the area has dissembled a M177 engine before to change fuel injector, so they don't want to do that unless we know it's absolutely the injector causing problem. Plus I am guessing if that's the case, code would show and balance rate could be much bigger.
7. Dealer had the same fault code and they don't know why, updated the powertrain software, no ECM update available.
I read through the forum and notice there's misfire and fuel injector leakage with the M177, but I doubt that's the case here since there is only one fault code P000028, otherwise there would be multiple codes showing up.
I was guessing could be either the filter or the oil pressure sensor giving wrong signal so the engine oil level is wrong all along. But my mech said the oil pressure sensor is rarely faulty and no code is shown.
So what do you guys think is triggering the CEL?
