[GipsyD]

I have a 2016 340i that's been throwing a bit of a tantrum lately. This all started when I was stuck in bumper to bumper traffic. I had to stop on a hill a few times as traffic crept along, which is when these issues arose.

The car started complaining about the brake system, and was throwing codes all over the place for all things brake related. Now, I had all brake discs and pads changed towards the end of last year by BMW, including brake fluid, as well as a brake flush.

The error codes are as follows -

- Brake System Fault. Please contact your BMW service partner.
- Daytime Pedestrian Warning Limited. Brake Intervention not possible.
- Frontal Collision Warning Malfunction. Brake Interventio not possible.
- Chassis Stabilization. Proceed Carefully.

These 4 always come up together, but the brake system fault goes away soon after it comes up. The rest are persistent. Everytime you drive the car, these errors come up.

I will post codes when I scan the car, but in the mean time, has anyone had this issue before? If so, what was the root cause of this issue? And how did you fix it?

Thanks for viewing!

[_F30_UK_]

I had a similar thing happen, although I had the ABS light and Tyre pressure monitor light come up. It happened very intermittently. I replaced an ABS sensor and all has been well since.

[GipsyD]

Originally Posted by _F30_UK_

I had a similar thing happen, although I had the ABS light and Tyre pressure monitor light come up. It happened very intermittently. I replaced an ABS sensor and all has been well since.

Did you get any codes for an ABS sensor?

Thanks for the reply. Appreciate it.

[ooshnoo]

How old the battery? If old, get a battery tester and test it. Lots of weird things like this happen when the battery starts to go...

[Billfitz]

Anything that uses wheel speed information won't function if there's an ABS fault.

[alohasurftoad]

i've had similar faults always caused by a faulty wheel speed sensor. i've had to change 3 wheel speed sensors and recommend using genuine BMW parts.

it's a fairly easy DIY

you need to get an OBDII code reader it will tell you which abs or wheel speed sensor that needs to be changed.
.

[GipsyD]

Originally Posted by ooshnoo

How old the battery? If old, get a battery tester and test it. Lots of weird things like this happen when the battery starts to go...

Battery was replaced at the end of 2021 after the car was taking longer to start. Checked voltage with a multimeter and the battery is healthy. Reading about 12.2V, so that eliminates that issue.

I had originally suspected the battery as well but I don't think the battery is the issue.

[GipsyD]

Originally Posted by alohasurftoad

i've had similar faults always caused by a faulty wheel speed sensor. i've had to change 3 wheel speed sensors and recommend using genuine BMW parts.

it's a fairly easy DIY

you need to get an OBDII code reader it will tell you which abs or wheel speed sensor that needs to be changed.
.

Thanks. Did you get any faults for the wheel speed sensors when pulling codes from the car? Anything at all?

[GipsyD]

Originally Posted by Billfitz

Anything that uses wheel speed information won't function if there's an ABS fault.

alohasurftoad said the same thing. To me, it's now the ABS Sensor

[Billfitz]

That's one possible cause. Scanning for error codes is a must. The battery is probably the least likely cause. There can be a low voltage issue, but more often than not that's caused by parasitic power drain by something. The dashboard and water pump are two examples.

[alohasurftoad]

Originally Posted by GipsyD

Thanks. Did you get any faults for the wheel speed sensors when pulling codes from the car? Anything at all?

the OBDII scanner indicated which wheel speed sensor was causing the error messages on my dash and display

basically if the wheel speed sensor is faulty, it disables the ABS because it doesn't have wheel speed info. in your situation, it may be the ABS sensor, as you suspect. the OBDII scanner will indicate which ABS sensor is faulty.

[GipsyD]

Originally Posted by alohasurftoad

the OBDII scanner indicated which wheel speed sensor was causing the error messages on my dash and display

basically if the wheel speed sensor is faulty, it disables the ABS because it doesn't have wheel speed info. in your situation, it may be the ABS sensor, as you suspect. the OBDII scanner will indicate which ABS sensor is faulty.

Did you use Bimmerlink? Or did you use another OBDII scanner? I'm using Bimmerlink, and I don't see anything pointing me to an ABS Sensor.

[GipsyD]

Alright, so these are codes that my car is throwing -

21A02D - Combustion Control Valve Lift
118002 - Mixture Control - Mixture Too Rich
101F01 - Throttle Valve Angle
118041 - Mixture Control - Mixture Too Lean - Large Deviation
118001 - Mixture Control - Mixture Too Lean

I think this is pointing to a bad VANOS Solenoid, but the car drives fine, and has all of it's power. I did the valve cover replaced, but that was about 2 years ago. TBH, I am not too worried about these codes, as they aren't hampering the car's performance.

48002C - LDM Function - High Level Operational Readiness - Brake Control Unit
480932 - Brake Fluid Sensor - Brake Fluid Too Low
E06C43 - Signal Status Invalid or brake chain not available
B7F343 - Backup Battery Failure

In total, this car has 9 codes now. I pulled these codes using Bimmerlink using a VGate BT OBD Adapter.

I don't see anything pointing to an ABS sensor. Only for a low brake fluid level, which I find highly unlikely considering I had the brakes, fluid and rotors changed at the end of last year.

Any ideas?

[alohasurftoad]

480932 seems the most suspicious. Are you able to clear it? If not, that's where I'd start troubleshooting from, especially since you did work on the brakes recently.

You may have to have a reputable indy mechanic asses as well.

I have an autophix scanner that is a foxwell knockoff. it is able to clear codes. the bimmerlink should be fine, though.

[Wires]

Originally Posted by alohasurftoad

480932 seems the most suspicious. Are you able to clear it? If not, that's where I'd start troubleshooting from, especially since you did work on the brakes recently.

You may have to have a reputable indy mechanic asses as well.

I have an autophix scanner that is a foxwell knockoff. it is able to clear codes. the bimmerlink should be fine, though.

100% agree with this. Is the fluid level fine? OP I could see how low fluid could trip those original codes.

You can check the fluid under the hood, next to the windshield, driver side. There are 3x 10mm plastic nuts that need to be turned CCW 1/2 turn to release the clips near the windshield, and then that plastic pulls straight off. Brake cylinder is right there.

[AlmondJayRoM3]

Are all those codes currently active or just stored?

Check battery voltage (both running and anfter sitting for a while)

Check brake fluid level while waiting.

[GipsyD]

Originally Posted by alohasurftoad

480932 seems the most suspicious. Are you able to clear it? If not, that's where I'd start troubleshooting from, especially since you did work on the brakes recently.

You may have to have a reputable indy mechanic asses as well.

I have an autophix scanner that is a foxwell knockoff. it is able to clear codes. the bimmerlink should be fine, though.

That's what I also thought, but since I had the brakes changed, I didn't think much of it. In my mind, if I'm low on brake fluid, that means I got a leak somewhere, as the brake system is a sealed system.

If the fluid reserve is low, then I'll take to a mechanic to check it out.

[GipsyD]

Originally Posted by AlmondJayRoM3

Are all those codes currently active or just stored?

Check battery voltage (both running and anfter sitting for a while)

Check brake fluid level while waiting.

These codes are stored as intermittent issues. After clearing the issues via OBD, the errors will come back after driving a bit.

[GipsyD]

Originally Posted by Wires

100% agree with this. Is the fluid level fine? OP I could see how low fluid could trip those original codes.

You can check the fluid under the hood, next to the windshield, driver side. There are 3x 10mm plastic nuts that need to be turned CCW 1/2 turn to release the clips near the windshield, and then that plastic pulls straight off. Brake cylinder is right there.

Will have a look at this. Might be something small like topping up brake fluid. But if that's the case, then that means I have a leak somewhere. To my knowledge, brake fluid isn't lost when using the system. I'm not sure if brake fluid thins over time, but if it does, then this brake fluid didn't even last 8 months.

[Wires]

Originally Posted by GipsyD

Will have a look at this. Might be something small like topping up brake fluid. But if that's the case, then that means I have a leak somewhere. To my knowledge, brake fluid isn't lost when using the system. I'm not sure if brake fluid thins over time, but if it does, then this brake fluid didn't even last 8 months.

Brake fluid is a closed system, and shouldn't go anywhere. Technically, it's hydroscopic (absorbs water) so it should gain volume over time, not lose it.

You might be in a case were it was just borderline for ever, and just tripped the sensor, or maybe the brake level sensor is bad?