u/Right-Cranberry-7194

Hi everyone, I’m looking for some advice about my E38 730d.
Today I drove from Valencia to Alicante (2h) and back. The trip there was completely fine: city driving, motorway, hills, accelerating normally, etc. The car felt good.
On the way back, shortly after leaving Alicante, the automatic transmission suddenly started making extremely loud “CLONK” noises when shifting up in D, accompanied by a fairly hard jerk. It happened several times and was strong enough that it genuinely felt like something underneath the car was going to fall off.
What’s strange is that about 30 minutes later, after driving gently at steady throttle on the motorway, it completely stopped. I then braked, let it downshift, accelerated again and went through several shifts in D, and everything was completely normal. I also stopped at a McDonald’s drive-through, restarted and drove away normally. I later drove at high speed on the motorway and there were absolutely no more noises or harsh shifts.
The car has also occasionally made a smaller clonk when downshifting or when going from coast to acceleration.
One thing I realized is that sometimes when parking I may have shifted from D to R or R to D before the car was completely stopped. I’m going to stop doing that from now on, but I’m wondering if I could have caused damage.
I’m planning to check the transmission and drivetrain before driving it much more: guibo/flex disc, center support bearing, transmission mounts, differential mounts, driveshaft play, ATF leaks, and read the EGS with INPA.
Would you guys suspect the transmission itself, or could this be drivetrain play/mounts/flex disc causing the huge clonk?
I was actually planning to drive the car for an hour trip and another hour back home tomorrow, but after today’s incident I’m not sure if I should risk another trip before checking it.
Any advice from E38 owners would be greatly appreciated.

Hi everyone, I’m looking for some advice about my E38 730d.
Today I drove from Valencia to Alicante (2h) and back. The trip there was completely fine: city driving, motorway, hills, accelerating normally, etc. The car felt good.
On the way back, shortly after leaving Alicante, the automatic transmission suddenly started making extremely loud “CLONK” noises when shifting up in D, accompanied by a fairly hard jerk. It happened several times and was strong enough that it genuinely felt like something underneath the car was going to fall off.
What’s strange is that about 30 minutes later, after driving gently at steady throttle on the motorway, it completely stopped. I then braked, let it downshift, accelerated again and went through several shifts in D, and everything was completely normal. I also stopped at a McDonald’s drive-through, restarted and drove away normally. I later drove at high speed on the motorway and there were absolutely no more noises or harsh shifts.
The car has also occasionally made a smaller clonk when downshifting or when going from coast to acceleration.
One thing I realized is that sometimes when parking I may have shifted from D to R or R to D before the car was completely stopped. I’m going to stop doing that from now on, but I’m wondering if I could have caused damage.
I’m planning to check the transmission and drivetrain before driving it much more: guibo/flex disc, center support bearing, transmission mounts, differential mounts, driveshaft play, ATF leaks, and read the EGS with INPA.
Would you guys suspect the transmission itself, or could this be drivetrain play/mounts/flex disc causing the huge clonk?
I was actually planning to drive the car for an hour trip and another hour back home tomorrow, but after today’s incident I’m not sure if I should risk another trip before checking it.
Any advice from E38 owners would be greatly appreciated.

Hi everyone,

I'm hoping someone with experience on E38/E39 CAN bus or ZF transmissions can point me in the right direction before I start replacing parts.

The car is a 2001 BMW E38 730d with the M57 3.0 diesel and ZF 5HP24 5-speed automatic.

Symptoms

- Transmission suddenly went into Transmission Failsafe.
- The gearbox is stuck in 2nd gear.
- Reverse still works.
- The engine starts and idles perfectly.
- The transmission doesn't seem to slip and I don't hear any obvious mechanical noises coming from it.
- Sometimes after restarting the car the behavior changes slightly, so it doesn't seem to be a completely permanent fault.

Fault codes

- EGS:
- Gear Monitoring
- Gear Monitoring 2
- Temperature sensor
- Engine speed while stationary
- GLUE symptom

- DDE:
- CAN communication faults
- Boost pressure sensor
- Boost control
- MAF related faults

- IKE:
- EGS communication fault

- DSC:
- Communication faults with EGS

- Basically several modules are reporting CAN communication problems.

Things I've already checked

- Battery voltage (engine off): 12.40V
- Ignition on: 12.04V
- Engine idling: 13.82V
- Engine idling with A/C on: 13.71V

- The alternator seems to be charging correctly.

Important background

- The car sat unused for around 2 months.
- I found evidence of rodents in the engine bay, so damaged wiring is definitely possible.
- I've read another Reddit thread where a faulty ASC module caused almost identical symptoms (Transmission Failsafe + CAN faults + EGS communication errors), so I'm wondering if this could be an electrical or CAN bus issue instead of an actual gearbox failure.
- I also had an intermittent red oil pressure warning a few times. Sometimes it briefly flickers when braking, and on a few occasions the full warning message appeared. Every time I stopped the engine immediately and checked the oil level, which was always correct. After restarting the engine, the warning disappeared and didn’t come back again for days or even weeks. The engine itself runs very smoothly, idles perfectly and sounds healthy with no knocking or unusual noises.

My questions

- Has anyone experienced this exact combination of Gear Monitoring + CAN faults + EGS communication errors?
- Can a faulty DSC/ASC module, damaged wiring, CAN bus issue or bad ground put the transmission into failsafe?
- Is there anything specific I should test before replacing the EGS or assuming the transmission itself is bad?
- Has anyone had this happen specifically on an M57 E38 or E39?

Tomorrow I'm taking the car to a workshop for a proper diagnosis, but I'd really appreciate hearing from anyone who's dealt with something similar.

PS: Before the transmission started acting up, I occasionally had engine limp mode. Since then, the transmission has gone into failsafe as well, so I’m wondering if both issues could share the same root cause (electrical, CAN bus, sensor, wiring, etc.

Thanks!