Failing alternator and glow plugs replaced .. more problems since, garage created ?

[Burdens]

Failing alternator and glow plugs were replaced by garage .. more problems since driving away, garage created ?

Before alternator issue  and glow plug replacement I had no issues other than hard to cold start.

Now I have these 3 errors ..

1. Mass or Volume Air flow A circuit

2. Lost communication with glow plug control module

3. Sensor reference voltage A circuit low

Looking for some insight before taking back to garage to have more money extracted

Car is 2010 300C SRT 3.0 CRD V6 (Mercedes diesel engine)

[jonnyjeep]

Hi there, if you have a code reader, then you can try to delete these codes, as they may have been stored by the PCM if the battery wasn't disconnected when the work was done, or the engine was started without the MAF sensor being plugged in.

If you don't have a code reader, then just disconnect the battery negative terminal for 30 seconds (standard reset time) & reconnect it. This should clear all fault codes & reset the PCM. The PCM should re-learn all it's parameters in less than 5 miles.

If the fault codes re-appear after that, then you have permanent faults

I find that glow plugs are always an issue with the CRD OM642 engine & even though it says it's a 'glow plug control module' problem, it's usually just one or two glow plugs that are at fault. A proper scan will tell you which plugs are a bit iffy.

There is another consideration....did you have NGK glow plugs fitted ? The reason I ask, is because I fitted a set of 6 NGKs a couple of years ago & after about 100 miles I had multple fault codes. When removing them, 4 of them were bent..... alas, they were fake NGK plugs (there are alot out there) & the dodgy ebay seller did not refund my money.

Went to local motor factors & bought some genuine Bosch glow plugs for not that much more than what the NGKs were on ebay & they were great. Three years later, two of them have failed, but doesn't really affect car. Will get two new Bosch ones before the cold weather sets in

Hope this helps

Edited October 19, 2023 by jonnyjeep