TAmes

Hello all,

Over the past few months I've had two transmission-related incidents, and I'd love to hear some perspectives on what steps to take to resolve this issue.

In both cases, I was cruising at 75-80 mph on the freeway, when all of the sudden the transmission malfunction light came on, the car seemed to downshift (revs went way up), and the car went into low power/limp mode. In both cases, I had to pull over to the side of the freeway and shut down the engine. Upon restarting the car after 5-10 minutes, everything functioned normally.

After the first incident, I brought my car in to my local service shop, but they couldn't figure out what was wrong with the transmission. They suggested that if it happened again (which it has), the best option might be to rebuild the transmission. I'm hoping there may be a more targeted solution to this issue.

Some other detail: I have the sport automatic transmission (SAT), and the car has only 35K miles on it.

I'd appreciate any perspectives from the board. Thanks in advance!

audiophool

Getting somebody to scan it would be my first step. If it lit up a transmission error, it would have set a code. Other problems can cause the transmission fail light to come on - mine did when the crank position sensor was going out.

Rebuilding the transmission as a first diagnostic would make me steer well clear of that shop.

TAmes

Thanks for the reply - I should have mentioned that the service center scanned for a transmission error, but nothing came up. Appreciate the tip re: the crankshaft sensor. Someone on another forum with a similar transmission issue mentioned replacing that sensor as well. Sounds like a good idea to replace that sensor as a first step.

-TA

seanjordan20

I would not replace anything until you get a code. There is no way your car had a trans failure and there was no code recorded. Is this a euro Indy shop or just a shop. If it is just a shop then they are not going to see the code because they do not have the right tools to troubleshoot a BMW. I went through the same thing for years and was told I needed a reman. I finally got feed up with it and trouble shot it myself and figured out the issue.

Before throwing parts at it and spending money get a code first. If you're going to have it for a while I would suggest you getting a copy of INPA and a K+DCAN cable to check things out for yourself. It will save you a lot of grief.

Their are a few DIYs about the E60 transmission on this forum that covers your issue extensively but without a code you're shoot darts in dark.

TAmes

Thanks, seanjordan20. Let me check again with my shop, which is a BMW service center. My SA said that they could see that a transmission malfunction error had occurred, but they couldn't isolate exactly why that malfunction occurred. I will definitely investigate further before doing anything since my plan is to keep this car for quite a few more years.

y0itzflip

if theres no code. check fluid. i had a similar issue when a transmission fluid line came loose from a bracket and rubbed a small hole and leaked out fluid. no codes just random transmission error that put me in limp mode and kicked car out of gear eventually.

unfortunately only way to check fluid is to basically drain it lol. good time for a transmission pan/gasket replacement.

Rez

I also think it's the Crankshaft Positioning Sensor. I would advise you to talk to the mechanic directly. My Indy mechanic is also the owner and SA, so it's a 1 man show! Here's my thread when I experienced it:

https://5series.net/forums/e60-discu...t-away-149561/

audiophool

For what it's worth, here's my thread from a couple years back. https://5series.net/forums/e60-discu...-147537/page2/

seanjordan20

Do not try to differentiate between "codes" and "errors". They are the same thing. Some trigger the CEL and some don't. All the information you can get will help figure out the issue. If you are at an actual BMW dealership just have them give you a printout of the errors on the transmission. They are not going to know because they don't fix transmissions they only replace so there's no need for them to diagnose that far.

audiophool

Not true. Lift the car high enough to get to the fill plug. Car has to be level and safely stable on jackstands etc. Run engine until transmission is at spec temperature (somewhre around 40C IIRC) then remove fill plug with engine still running. If fluid dribbles out the level is fine. If not, add the correct fluid until it starts to dribble out, then replace fill plug.