2011 135i E82 Msport

bung206 · 10-24-2016, 10:25 PM

Hello everyone

I'm still trying to diagnose the issue with my car which originally started out with the ABS/Brake/DSC lights. I did what you'd normally do in this situation - scan it and find out which sensor is faulty, then replace that sensor. At the time I had an intermittent airbag light as well which I believed to be related to the DSC problem.

The thing is every time I replaced a wheel speed sensor, the fault jumped to another. I went through 2 sensors and the fault jumped each time. Replace FR - fault jumps to FL. Replace FL, fault jumps to RR. But at least now, the fault goes away sometimes - all 4 wheel speed sensors work correctly.

Yesterday, I managed a 40 mile drive. Stopped to go into a store - was probably stopped about 15-20 minutes. Came back out and drove off, and while accelerating the car starts jerking back and forth and "Transmission Fault" is shown on the iDrive display. A few moments later, "Transmission Overheating" is shown, but only for 2-3 seconds then dissappears.

I pulled over, checked everything and it seemed fine. After restarting car, it drove fine for the 40 mile journey home (no gearbox overheating faults!)

I am really at a loss as to how the gearbox could overheat especially when I wasn't being very rough with it?

The car has recently had a new battery. It was on its original battery so I figured I'd have it changed just in case. The battery was of the correct size, type & rating and was "registered" correctly with the car also.

I have checked under the hood for any obvious breaks in wiring, wiggled the wiring with the engine running to make sure everything runs smoothly... to no avail.

I have also rang my local dealership to confirm that my car is NOT part of the mail fuse-box positive battery terminal wiring replacement recall.

So what else could this be? At this point I'll try anything.

bung206 · 11-06-2016, 06:23 PM

I've finally resolved this.

Turns out I really did have a faulty rear right wheel speed sensor that was sending data intermittently. A broken wheel speed sensor on the rear is a big deal for a RWD car with a DCT gearbox. The gearbox ECU needs accurate wheel speeds to decide shifting parameters. When the wheeel speed data is not present or the ECU thinks it's implausible, it will attempt to read the wheel speed using the output shaft which apparently is not very accurate, causing it to go into a fail safe mode? This causes the box to shift conservatively (and slip the clutch a lot I'm guessing). So the gearbox really was overheating.

I replaced the faulty wheel speed sensor and the fault has gone away completely and the gearbox has not overheated after over 300 miles of driving in all conditions (hard pulls, normal driving, heavy traffic driving and freeway cruising).

The front right and front left Wheel Speed sensors I pulled really are broken - when I put them back on the car I get NO wheel speed data at all. Maybe I part of a bad batch or similar. So there you have it. Turns out 3 wheel speed sensors can fail at the same time.

iEuropa · 11-08-2016, 08:24 AM

I've had improbable stuff like this happen before. Sometimes you chase your own tail before giving up on accepting that it all went wrong at once. Glad you got it fixed!

Chihuahua · 11-17-2016, 07:05 AM

bung, glad you solved your problem and also THANK YOU for following up on your thread, it will more than likely help someone in the future.

10-24-2016, 10:25 PM	#1
bung206 Private 35 Rep 50 Posts Drives: E82 135i MSPORT Join Date: May 2016 Location: Australia iTrader: (0)	2011 135i E82 Msport - assorted faults Hello everyone I'm still trying to diagnose the issue with my car which originally started out with the ABS/Brake/DSC lights. I did what you'd normally do in this situation - scan it and find out which sensor is faulty, then replace that sensor. At the time I had an intermittent airbag light as well which I believed to be related to the DSC problem. The thing is every time I replaced a wheel speed sensor, the fault jumped to another. I went through 2 sensors and the fault jumped each time. Replace FR - fault jumps to FL. Replace FL, fault jumps to RR. But at least now, the fault goes away sometimes - all 4 wheel speed sensors work correctly. Yesterday, I managed a 40 mile drive. Stopped to go into a store - was probably stopped about 15-20 minutes. Came back out and drove off, and while accelerating the car starts jerking back and forth and "Transmission Fault" is shown on the iDrive display. A few moments later, "Transmission Overheating" is shown, but only for 2-3 seconds then dissappears. I pulled over, checked everything and it seemed fine. After restarting car, it drove fine for the 40 mile journey home (no gearbox overheating faults!) I am really at a loss as to how the gearbox could overheat especially when I wasn't being very rough with it? The car has recently had a new battery. It was on its original battery so I figured I'd have it changed just in case. The battery was of the correct size, type & rating and was "registered" correctly with the car also. I have checked under the hood for any obvious breaks in wiring, wiggled the wiring with the engine running to make sure everything runs smoothly... to no avail. I have also rang my local dealership to confirm that my car is NOT part of the mail fuse-box positive battery terminal wiring replacement recall. So what else could this be? At this point I'll try anything.
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11-06-2016, 06:23 PM	#2
bung206 Private 35 Rep 50 Posts Drives: E82 135i MSPORT Join Date: May 2016 Location: Australia iTrader: (0)	I've finally resolved this. Turns out I really did have a faulty rear right wheel speed sensor that was sending data intermittently. A broken wheel speed sensor on the rear is a big deal for a RWD car with a DCT gearbox. The gearbox ECU needs accurate wheel speeds to decide shifting parameters. When the wheeel speed data is not present or the ECU thinks it's implausible, it will attempt to read the wheel speed using the output shaft which apparently is not very accurate, causing it to go into a fail safe mode? This causes the box to shift conservatively (and slip the clutch a lot I'm guessing). So the gearbox really was overheating. I replaced the faulty wheel speed sensor and the fault has gone away completely and the gearbox has not overheated after over 300 miles of driving in all conditions (hard pulls, normal driving, heavy traffic driving and freeway cruising). The front right and front left Wheel Speed sensors I pulled really are broken - when I put them back on the car I get NO wheel speed data at all. Maybe I part of a bad batch or similar. So there you have it. Turns out 3 wheel speed sensors can fail at the same time.
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11-08-2016, 08:24 AM	#3
iEuropa Private 22 Rep 66 Posts Drives: 2008 135i Join Date: Jun 2016 Location: Baltimore iTrader: (0)	I've had improbable stuff like this happen before. Sometimes you chase your own tail before giving up on accepting that it all went wrong at once. Glad you got it fixed!
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11-17-2016, 07:05 AM	#4
Chihuahua Brigadier General 4075 Rep 3,204 Posts Drives: E30 329iS, E65 Alpina B7 Join Date: May 2012 Location: ATL iTrader: (0)	bung, glad you solved your problem and also THANK YOU for following up on your thread, it will more than likely help someone in the future.
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