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Having an issue with my 2004 E320 4Matic Sedan lately. Most recently, I had the rear dif. replaced along with a rear axle. Since than, the red brake light "Brake, reduced braking effect, visit workshop" is lit up in my instrument cluster (photo attached). It doesn't beep, just stays lit red. Car drives perfectly fine and the brakes as well. I had asked the tech who swapped out my rear diff. about it and they had told me it was probably there before they touched the vehicle (which it 100% wasn't) but I'm not going to sit there and argue with them. There's also a weird clicking noise coming from the rear driver side brake, nothing looks to be abnormal however.
Any ideas what this could be? Used a typical OBD2 scanner and no codes, just the annoying red brake light on my dash that never goes away.
You also have the ABS light, might have something to do with the brake warning, or not, but without the codes everything is just a game of guess. So first thing to do is to find someone with a scanner that goes into brake system, then it's easier to diagnose the problem.
You also have SBC brakes so if it turns out it's the pump, the dealer will fix it for free as it has a 25 year extended warranty with no mileage limit. But if it's something else like the rear parking brake shoes or you have a leak, then it wouldn't be covered and it will be super expensive at the dealership. Don't clear any codes if it's related to the brakes as the dealer would need to see them before fixing the SBC brakes for free.
Don't mess around with the SBC system, get a scanner which is able to read the codes properly (star/xentry or a decent Autel etc).
Word of warning: I had the assisted brakes fail whilst doing 60mph on the highway and I cannot recommend that to anyone. Root cause was the SBC unit failing, I got it replaced in 2023 for free by MB by the extended warranty (I live in the Netherlands btw). These were my error messages: https://mbworld.org/forums/c219/8443...ml#post8651162
Guess I'll have to invest in the scanner, not something I really wanted to purchase but I pretty much have everything else in regards to tools. Are the Autel scanners any good/will they be able to do pretty much everything I need to do in regards to Mercedes? I've owned a few of these cars in the past (C300, E320, 560SEC) and Mercedes is pretty much what I purchase when I buy vehicles so I want to make sure this would be a good investment before just sending the car to a Euro mechanic whom I typically use when a job is "too big" or I don't have the necessary equipment.
Here's the scanner I'm looking at in the link referenced below;