Differential gone :(

[Dibby]

Hi all, 1st post here and not a good one. 45k miles, late ‘16 m4 which I’ve owned for 1 year. Yesterday I got a “drivetrain possible to continue journey” briefly. Once I clicked ok to the message it went away and didn’t return until about 30 miles later. When it came back, I also had a “rear axle differential lock” and “driving stabilisation. Drive moderately.” Errors, this put me in limp mode with an orange warning and came to a stand still. I can barely move forward or in reverse, the DCT seems to want to start in 2nd, and it revs to about 2-3k before moving. Is this likely to be a full differential change, or more likely to be sensor or a control unit. It’s heading to the garage later this week, but was really hoping someone would have seen these 3 errors and symptoms.

[WordOnRoad]

Did you scan it and try to pull any of the actual fault codes?

[Dibby]

Originally Posted by WordOnRoad

Did you scan it and try to pull any of the actual fault codes?

The AA found these but couldn’t clear them and not sure which are related to the differential.

Engine control 1 - PBD / Motronic MED 17 (M) UDS1F1A90 - 5V reference voltage circuit 1. Error Message : Value outside specified range.103008 - Accelerator pedal position sensor 1. Error Message : Voltage too low.103002 - Accelerator pedal position sensor 1. Error Message : Short circuit to earth.123414 - Exhaust-gas turbocharger control unit 2. Error Message : Wastegate closed. / pos.not found.123402 - Exhaust-gas turbocharger control unit 2. Error Message : Malfunction at cold start.120408 - Boost pressure control. Error Message : Safety shutoff.165014 - Intermediate shaft sprocket hp pump. Error Message : Substitute value active.121533 - Pressure comparison, boost pressure vs. ambient. Error Message : Pressure too low.121531 - Charge air pressure. Error Message : Pressure too low.135808 - Position sensor variable valve control. Error Message : Faulty operation.123424 - Exhaust-gas turbocharger control unit 2. Error Message : Wastegate closed., start n. found.11A002 - Fuel high-pressure system: Pressure. Error Message : Pressure too low.11AA03 - Fuel high-pressure pump. Error Message : Pressure too low.11AA05 - Fuel high-pressure pump 2. Error Message : Pressure too low.121202 - Boost pressure sensor. Error Message : Pressure too high in overrun.135608 - Variable valve control. Error Message : No movement detected.

[Inquisitor]

Originally Posted by Dibby

Hi all, 1st post here and not a good one. 45k miles, late ‘16 m4 which I’ve owned for 1 year. Yesterday I got a “drivetrain possible to continue journey” briefly. Once I clicked ok to the message it went away and didn’t return until about 30 miles later. When it came back, I also had a “rear axle differential lock” and “driving stabilisation. Drive moderately.” Errors, this put me in limp mode with an orange warning and came to a stand still. I can barely move forward or in reverse, the DCT seems to want to start in 2nd, and it revs to about 2-3k before moving. Is this likely to be a full differential change, or more likely to be sensor or a control unit. It’s heading to the garage later this week, but was really hoping someone would have seen these 3 errors and symptoms.

Are your bushings worn?

[Sharpie]

Originally Posted by Dibby

Hi all, 1st post here and not a good one. 45k miles, late ‘16 m4 which I’ve owned for 1 year. Yesterday I got a “drivetrain possible to continue journey” briefly. Once I clicked ok to the message it went away and didn’t return until about 30 miles later. When it came back, I also had a “rear axle differential lock” and “driving stabilisation. Drive moderately.” Errors, this put me in limp mode with an orange warning and came to a stand still. I can barely move forward or in reverse, the DCT seems to want to start in 2nd, and it revs to about 2-3k before moving. Is this likely to be a full differential change, or more likely to be sensor or a control unit. It’s heading to the garage later this week, but was really hoping someone would have seen these 3 errors and symptoms.

This fault is not likely to be the diff.

The errors shown such as 'rear axle differential lock' are all part of the limp mode shutting systems down, not necessarily a problem with that system.

I had exactly the messages you describe and the extreme limp mode you describe, DCT in straight to 2nd, super slow engaging etc

My fault was that a sensor inside the valvetronic motor had gone short circuit. This means all the other sensors that use the same power as the valvetronic motor sensor suddenly cant read and the engine has no info from them and enters a very restrictive limp mode.

Your long list of errors are all the things the car suddenly has no info from. I suspect something has gone short circuit to ground. If you can trace and unplug that sensor or component your car may become much more alive, or at least you will know what part has failed.

The valvetronic plug is under the engine cover on the left.

Dealer replaced my vavletronic motor (in warranty) car was all good.

[Dibby]

Originally Posted by Sharpie

This fault is not likely to be the diff.

The errors shown such as 'rear axle differential lock' are all part of the limp mode shutting systems down, not necessarily a problem with that system.

I had exactly the messages you describe and the extreme limp mode you describe, DCT in straight to 2nd, super slow engaging etc

My fault was that a sensor inside the valvetronic motor had gone short circuit. This means all the other sensors that use the same power as the valvetronic motor sensor suddenly cant read and the engine has no info from them and enters a very restrictive limp mode.

Your long list of errors are all the things the car suddenly has no info from. I suspect something has gone short circuit to ground. If you can trace and unplug that sensor or component your car may become much more alive, or at least you will know what part has failed.

The valvetronic plug is under the engine cover on the left.

Dealer replaced my vavletronic motor (in warranty) car was all good.

Thanks, I’m leaning towards something like that now too. Could it be the crank hub? I’ll know for sure later this week. Today it wouldn’t start. It turned over but didn’t start. Spluttered once or twice.

[Sharpie]

Originally Posted by Dibby

Thanks, I’m leaning towards something like that now too. Could it be the crank hub? I’ll know for sure later this week. Today it wouldn’t start. It turned over but didn’t start. Spluttered once or twice.

This is 100% what mine did, after the limp mode, the next day it developed to crank no start. When you hear your F8X crank no start you think the worst but I doubt it. I'm obviously influenced by my experience / cant help but compare but this sounds 100% like the valvetronic motor has gone bad.

You may know but now it wont start, you wont be able to get it into neutral to move the car without removing the undertray, disconnecting the park actuator and holding it out of park with a tie wrap.

[Dibby]

Originally Posted by Sharpie

This is 100% what mine did, after the limp mode, the next day it developed to crank no start. When you hear your F8X crank no start you think the worst but I doubt it. I'm obviously influenced by my experience / cant help but compare but this sounds 100% like the valvetronic motor has gone bad.

You may know but now it wont start, you wont be able to get it into neutral to move the car without removing the undertray, disconnecting the park actuator and holding it out of park with a tie wrap.

Thanks for your messages, I’ll keep you updated later this week. It’s being collected tomorrow. They said they can use skates to move it onto the flatbed.

[OnlyGerman]

Geesh so many valvetronic motor issues on these

[AlmondJayRoM3]

Originally Posted by Dibby

Thanks, I’m leaning towards something like that now too. Could it be the crank hub? I’ll know for sure later this week. Today it wouldn’t start. It turned over but didn’t start. Spluttered once or twice.

Crank hub is not going to cause all those codes

[Dibby]

Originally Posted by Sharpie

This is 100% what mine did, after the limp mode, the next day it developed to crank no start. When you hear your F8X crank no start you think the worst but I doubt it. I'm obviously influenced by my experience / cant help but compare but this sounds 100% like the valvetronic motor has gone bad.

You may know but now it wont start, you wont be able to get it into neutral to move the car without removing the undertray, disconnecting the park actuator and holding it out of park with a tie wrap.

Your experience was spot on. Had confirmation today that the valvetronic actuator (part no. 11377603979) is faulty and is being replaced. Thanks.

[Jbrown7403]

Sounds like great news and a pretty simple fix. Love to know if this completely resolves the original issue.

[Sharpie]

Originally Posted by Dibby

Your experience was spot on. Had confirmation today that the valvetronic actuator (part no. 11377603979) is faulty and is being replaced. Thanks.

You're welcome. Thanks for sharing the update, glad to hear you are getting it sorted.

The replacement is an interesting job.

As OnlyGerman noted, having been on the F8x M forums for 5 years now, valvetronic problems are one of the more common engine issues I have seen crop up. I see on the B58 platform the valvetronic motor moved from inside the valvetrain to an external motor, seems like a better place to me !

https://youtu.be/jQW1IeaipsU

[FatHulk]

Had a similar issue happen to me yesterday. When I started the engine, got a ton of warning messages, low tire pressure, driving stabilization, rear differential lock, pedestrian collision warning malfunction. Drove okay but pretty sure it was in limp mode. Going to bring it in next week and hopefully it's nothing major!