ASpec818

I was accelerating today around 40mph and all of a sudden the car downshifted to a low gear and it felt like someone rear ended me. The transmission malfunction error message came on and it wouldn't up shift anymore. No cel came on. Seems like the car is stuck in 2nd or 3rd gear.

I recently had the transmission fluid flushed and the mechatronics sleeve replaced because it was leaking. Any ideas what it could be? The tranny was driving fine before all of this.

My 05 545i only has 79k miles.

I just restarted the car and the fault went away, but I haven't driven the car yet. Is there an error code that can be pulled read with a scanner when this occurs?

seanjordan20

If the CEL did not come on then the only way you pull the message is by INPA or any other BMW progam that read messages. BMWs have error messages and information messages. I am sure you will have one or two in the system.

Did you check to see if you are not leaking any fluid or if the mechatronic was hooked up correctly. Who did the refill? Did they follow the proper procedure. You might not have enough fluid in the trans. Should be around 6L that was put back in.

ASpec818

Just pulled the fault code from the transmission ecm, and it was 4F85- something about gear ratio clutch E. And it shows that it occurred only once. Should I be worried? The car drives perfectly except for the common 35-40 mph hiccups. They did an adaptation reset.

The tech had typical BMW dealer mindset and said I would need a new transmission if it happens again.

KyleB

check the DIY thread. Been there, done that. If it did it once, it's going to do it again sooner than later. No, resetting adaptations will not fix it.

No, you probably do NOT need a new transmission. That is such a lazy diagnosis, shame on your mechanic for that. One transmission hiccup and one fault code means you need a new transmission. By that logic, one engine misfire and one fault code for 'misfire cylinder 1' means you need a new engine, right? Of course not....

good luck, read through the thread in the DIY section and PM me if needed. Could be solenoids, could be low fluid due to a leak, could be the bridge seal, could be some or all of the above.

mrottenborn

Hi, I have a different car (2008 528xi with 107K miles) but just solved a similar problem and thought I'd pass along the solution in case it helps you.

The initial symptoms were exactly the same as yours - driving along at 40-50 mph when the car went into "limp home mode" and dropped into second gear with a big jolt. The service display illuminated showing a "Transmission Fault" message. I shut off the car, restarted it, and all was fine for a few days until it happened again. This time we limped to the dealer, who read the fault codes and recommended replacement of the steering angle sensor ($925) and crankshaft position sensor ($675) for starters, before digging in to the transmission.

I declined the repair and read the codes with my generic Actron OBD-II reader at home. I did get a crankshaft position sensor fault plus a few other codes, none related to the steering angle sensor.

I ordered the crankshaft position sensor (not to be confused with the multiple camshaft position sensors these cars have) for $75 and installed in in a couple of hours. It fixed the entire problem with no other repairs required, but I took the opportunity to replace the transmission pan/filter and fluid at the same time.

There's not much information about this fault on the message boards but apparently a failing crankshaft position sensor can present as a variety of faults including transmission problems. Other symptoms are difficult starting with long cranking times, and rapid fluctuations of engine speed on the tachometer (+/- 500 rpms every couple of seconds).

You may want to check this before suspecting a transmission fault.

Good luck,
Mike