[anjuna]

Hi there,

Not an avid visitor of the X3 forums, as most of my expertise and hobbies are with the drivetrain of the F25 X3, which are most commonly shared and modified on the E90 N55 forums.

Vehicle - 2011 BMW F25 X3, xDrive 35i (3.0L N55) with 8 speed automatic (ZF 8HP45)

My vehicle has been meticulously maintained by myself. No long standing issues persist before I repair them. I've done standard maintenance, suspension replacement, brake replacement, transmission fluid changes... you name it and I've done it.

However, I have an issue that has come up recently without any major changes or maintenance corresponding with the issue.

I have received a slew of codes from, what I believe, is the ABS module:
1B0A21 - Rough Road Detection - No wheel RPM signal received

1B0A60 - Driving speed plausibility; Minimum speed under load implausible

1B0A61 - Driving speed plausibility; Minimum speed when in coasting / overrun mode implausible

1B0A62 - Driving speed plausibility; Speed signal implausible

1B0A64 - Driving speed, Wheel RPM sensor rear/left, signal change: not plausible

1B0A65 - Driving speed, Wheel RPM sensor front/left, signal change: not plausible

1B0A66 - Driving speed, Wheel RPM sensor rear/right, signal change: not plausible

1B0A67 - Driving speed, Wheel RPM sensor front/right, signal change: not plausible

I also get the following codes from the transmission, though I'm not sure it's an issue or more of a sanity check:

420611 - Transmission input-RPM sensor 2: Supply voltage outside of lower value range.

CF2F02 - Signal (actual speed of rear left/front left/rear right/front right wheel) invalid, transmitter DSC


Now, I think it's relatively safe to assume that I did not experience a simultaneous fault of every single wheel speed sensor, as every other case I've seen has had the first 3 or 4 codes listed, along with ONE wheel speed sensor. However, I am getting faults for all 4 wheel speed sensors.

Additionally, I get the whole lot of dash lights for vehicle stability, restraint system malfunction, "ABS - Brake System Drive Moderately," and the lot. If I start cruise control, it fails as expected, because the DME does not know the speed it is traveling. This is confirmed by evaluating the DME's vehicle speed, which remains at "0" throughout all driving.

The lights on the dash tend to cascade within the first few minutes of driving. I will start the car and it will alert me of a braking system malfunction and ABS system malfunction immediately. As I begin to drive, I will first lose power steering, then I will receive a "Restraint system malfunction" as well.

Then, the vehicle continues to drive "normally" after this point. No limp mode, no driveability issues, brake performance is normal (though, ABS does not function) and, other than the lights, warnings, and chimes, I do not experience any issues with the car's reliability or performance. The vehicle still makes ~19psi and all is well.

Oddly enough, I still receive an accurate vehicle speed on my cluster. I have noticed the following:
1. Intermittently, the speedometer will hang at 40mph, even though the vehicle speed is greater than 40mph, then suddenly rise to match the correct vehicle speed.
2. Intermittently, when coming to a stop, the brake pedal will push harder against my foot, as if there is a reduction in brake boost performance. The vehicle comes to a stop at the same speed and this does not appear to be a safety issue, but it's something worth noting.
3. The loss of power steering is rather odd, but given that it is EPS and not hydraulic, it would make sense that some speed related logic is not being passed to the EPS for assistance.

I have tried to disconnect the ABS unit entirely, assuming there may be a total fault there, but additional codes resulted (that I did not document), so the ABS unit must be passing some messages along canbus. Driving in this manner resulted in the same issues, but I had zero speedometer reading.

If I clear the codes, they come back immediately after driving.

I have not taken ISTA to the car yet, as I do not want to introduce more variables and changes into the situation, given that nothing has been changed since these problems have arisen.

tl;dr - I didn't make any changes to my vehicle, but now I have ABS/DSC codes, a christmas tree of a dashboard, MULTIPLE vehicle speed sensor implausible codes, and have no clue what a potential issue is for this poly-issue fault.

I would sincerely appreciate anyone's insight into the cause or a potential path to troubleshoot / remedy this issue.