[bigmixx11]

I have 2019 M5C with around 38,600 miles on it. I've had it about 15 months now. I had taken it on a road trip over the weekend and put about 700 miles on it. Got back home Monday evening and it sat in the garage until yesterday. I decided to wash it as it was filthy due to the rain and when I hit the button the car stumbled to start and idled rough and when I saw the drivetrain malfunction I shut it down immediately. The malfunction went away, I checked the menu and it said everything was green. I waited about 15 minutes and started it again and everything seemed normal. Went through the cold start process and idled normally like always. I pulled it out, washed it and put it back in the garage. Didn't drive it at all.

Today, I started it up again and no code. Let it warm up and took it out for short drive to test it. Got it up to temp and the car ran like normal.

The car did have a coolant tank leak in its history but was replaced before I bought it by the original owner. I had the spark plugs replaced at around 34,000 miles when the car gave me the notification to replace them. I asked for the old plugs and some of them were covered with dried coolant. Possible that I'm starting to have some complications from the leaky tank or could it be something else?

[MaulerZ]

I had my coolant tank replaced. Everything was fine for a few days, then all of a sudden I had a drivetrain malfunction.

Took it back to the dealer. Turned out that I needed four new coil packs and two new spark plugs. The dealer didn’t say why, but I’m guessing the tech spilled coolant onto my coils when replacing the coolant tank, which then ruined two spark plugs.

Maybe a similar thing happened to you?

[pbonsalb]

Another possibility is the low pressure fuel pump.

[bigmixx11]

Originally Posted by MaulerZ

I had my coolant tank replaced. Everything was fine for a few days, then all of a sudden I had a drivetrain malfunction.

Took it back to the dealer. Turned out that I needed four new coil packs and two new spark plugs. The dealer didn’t say why, but I’m guessing the tech spilled coolant onto my coils when replacing the coolant tank, which then ruined two spark plugs.

Maybe a similar thing happened to you?

Well the original owner of the car had the tank replaced about 8 months before I bought the car so that could’ve happened to him. The spark plugs are from about 6 months ago when I had them changed. The car was not showing any issues over last 15 months since I owned it.

[bigmixx11]

Originally Posted by pbonsalb

Another possibility is the low pressure fuel pump.

Ah ok. I assume this would cause that rough idle and hard start as it did the other day?