DSC + Yellow brake light

[ComradeNick]

Driving to work today I had the DSC light and yellow brake light come on at the same time. I turned my car on and off at a red light, which made it go away for a few seconds before coming back on. The car didn't seem to have any issue driving, felt normal but then again I wasn't really pushing it with an unknown light.

At work I looked up that is was a DSC issue and ran it through the scanner which came up with code: 5E24 on a Snap-On. I looked up the code and from what I'm understanding it points to an issue with the master cylinder, or its pressure sensors. The solutions are to replace the master cylinder and bleed the brakes.

On the 5 mile drive home the light stayed off and I was able to switch the DSC on and off with any issues. I also checked the brake fluid reservoir and it was exactly at max.

My question is does anyone have experience with this issue on their car and did replacing the Master cylinder fix it, and also is it safe to drive the car under normal conditions for the time being until I decide to have it repaired at my work or take it to my mechanic. Thanks

[PetesZ]

Try flushing the brake fluid first.

Check tire pressure

Clean wheel sensor

Then the pressure sensor

It means your abs and traction control are completely off. No damage just full analog mode on brakes. I run this way on every track day.

[3LiterStraightSix]

Had this same issue. My first step was changing out a wheel sensor. It 100% fixed the issue. I did not even buy new, just picked one out dirt cheap at a junkyard.

There are a couple of different scenarios based on which sensor went bad. Does your cruise control still function when the DSC lights are on? How about your speedometer? Each wheel sensor is related to a certain function.

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[az3579]

If you're getting that particular code, it'll probably be the brake pressure sensor. Master cylinder is fine.

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[pedro2u]

I've been having that issue since May (DSC and yellow brake - no ABS light). Beep and lights go on at some point almost every day but goes out after restart. I have these codes even after clearing:

5E20/A0 - Pressure sensor 1 electrical faulty.
5E24/A0 - Pressure sensor 1/2 not plausible.
5E1A/A0 - CAN DME/DDE Signal Error.
5E5C/20 - RPA push button Error.
5E21/A0 - Pressure sensor 2 electrical faulty.

Doesn't seem like both wheel speed sensors can be bad. So far, all I've done is pull the right rear speed sensor and clean it. Others have claimed that fixed their issue, but not mine. And with both pressure sensors ($171 each on FCP) showing faults, swapping them at the DSC doesn't make sense. Next step is to throw money at a new DSC/Master Cylinder (34336785666 $425 on FCP), but your thread inspired me to check for a used DSC on eBay - which I just purchased for only $30 with 2 pressure sensors from a 99.6% eBay feedback salvage yard claiming it's in good working condition. Worth a shot. So that's next for me. Good winter project when I put it away for the winter. Until then, no problems with driveablitiy what so ever

[pedro2u]

and 50sKid has a great video on replacing:

https://www.youtube.com/watch?v=CvyVCwCAx1Q

[pedro2u]

well it appears I should have watched the entire 50sKid video. The pressure sensors are on the master cylinder which RealOem call calls the Master Cylinder/DSC - so that's what I picked up on eBay. Wrong.... it appears the DSC itself is part number 34516759074 below the master cylinder. New it's about $2K! And RealOem doesn't even list it for my car when I search by VIN. So, time to rethink this before I throw $500+ for a used one. Right now I don't mind the lights :)

[san]

I use to get those lights quite often. Swapped the fluid and I got it back maybe once over the last year.


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[3LiterStraightSix]

I was going to say! A $30 DSC is godly [emoji38]

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[Vas]

I had to replace one of the pressure sensors before. Iirc it is $100 per sensor.

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[pedro2u]

I flushed by brake lines 4K miles ago (last November), so that probably won't be my solution. And $30 for the salvage master cylinder - it also comes with both pressure sensors, so still happy with that:thumbsup

[ComradeNick]

Try flushing the brake fluid first.

Check tire pressure

Clean wheel sensor

Then the pressure sensor

It means your abs and traction control are completely off. No damage just full analog mode on brakes. I run this way on every track day.

I haven't gotten the light since the first came on, but just out of curiosity I checked my tire pressure since It was the easiest to do. They were 30psi all around, even though the manual recommends 32 front 38 rear. I haven't touched them since I bought them so It makes me question what else the PO missed, even though he was a bmw tech.

Is there any easy way to clean and check the wheel and pressure sensor without lifting the car? If not ill probably take the car in to have the brake fluid flushed and check on it then.

[ComradeNick]

Had this same issue. My first step was changing out a wheel sensor. It 100% fixed the issue. I did not even buy new, just picked one out dirt cheap at a junkyard.

There are a couple of different scenarios based on which sensor went bad. Does your cruise control still function when the DSC lights are on? How about your speedometer? Each wheel sensor is related to a certain function.

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I didn't notice any issues with the speedometer and I've never used the Cruise control. I'm leaning towards this being the issue since when I had the car plugging into the scanner the brake pressure circuits where equal and responsive to brake pressure. Circuit 1 was consistently 10 psi lower but I don't think that's a big issue.

Do you remember the part no. on the sensor by chance?

[pedro2u]

Responding to ComradeNick, when I cleaned my sensor, I found it easiest to pull the wheel to get easy access to remove/disconnect and/or clean the sensor. 6mm allen head bolt holds it in

From RealOEM, appears the 2 rear sensors are the same part, but the fronts are different part numbers:

Pulse generator, ABS front right 1 34526792896
Pulse generator, ABS front left 1 34526792897
Pulse generator, ABS rear 2 34526752702