[vattyboy]

Hi, my fellow bhpians,

For the past couple of days, my Mercedes-Benz CLA was showing an error of - Abs and Traction control inoperative on the speedometer. This warning vanishes sometime on its own and sometime it again comes back.

When this sign comes car goes into hazard mode in which the power steering deactivates, the Cruise control shuts off, gear shifting is not smooth anymore it becomes jerky. But there is no restraint on the speed limit

Today I decided to get my car diagnosed at Mercedes ASS


SA began with the OBD scan and found a fault in the front axle left side rpm sensor , he figured out that it needs to be replaced and I gave permission for the same.



The total cost of replacement of the 1 rpm sensor came out to be Rs 5200(The cost of the rpm sensor is RS2700 and Rs 2700 for Labor).



Speaking about the overall experience of the ASS, I found their work very lazy. I reached ASS at sharp 10 am and they took nearly 6 hrs to complete this small job.

[GTO]

Thread moved from the Assembly Line to the Tech section. Thanks for sharing!

[Dr.AD]

Originally Posted by vattyboy

SA began with the OBD scan and found a fault in the front axle left side rpm sensor , he figured out that it needs to be replaced and I gave permission for the same.

Thanks for sharing your experience and I am glad you found a quick solution.

This is actually a very common problem with most of the Euro cars. That warning you saw on the instrument cluster almost certainly means a failed speed sensor. It has happened to many of us and has been documented many times on this forum.

For example, here is my experience: https://www.team-bhp.com/forum/long-...ml#post5438623

And here is experience of @graaja who had the exact same warning and the exact same solution: https://www.team-bhp.com/forum/long-...ml#post5449833

I know of at least five other cases in BMW and Mercedes where this happened. So yes, this is extremely common and nothing to worry about.

However, a key thing to note is that once one speed sensor fails, it is very likely the other side sensor will fail soon too. This is why BMW changes these in pairs (they changed both of my rear speed sensors when the fault was in one of the rear speed sensors). In case they changed only one speed sensor in your case, be prepared to face a similar error again and do not get surprised that time.

[vattyboy]

Originally Posted by Dr.AD

Thanks for sharing your experience and I am glad you found a quick solution.

Hello DrAD,
A]. I talked with SA yesterday and he said this same warning can come in these cases-
1. Faulty Abs sensor
2. Faulty Rpm Sensor.
3. Transmission issue
4. Engine oil issue
and it is very difficult to guess the exact fault without an obd scan.
I am happy that 1st case didn't occur in my car as the cost of the abs sensor is approximately Rs20k.

B]. I faced a similar issue in Kolhapur 2 years ago when I was traveling to goa, so I got my car examined at Mercedes silver star, that moment it was because of faulty rear left rpm sensor, and they recommend changing both the rear sensors but I got only one changed that time, 2 years passed since then and rear right sensor never troubled me. So this time also I got only the faulty sensor replaced.

I read your threads DrAD, you share very interesting things, information and your writing skills are phenomenal

[Jeroen]

Originally Posted by vattyboy

1. Faulty Abs sensor
2. Faulty Rpm Sensor.

Shocking to hear this, relatively simple job took so long. On some cars it can be quite a problem getting these sensors removed as they get very stuck. E.g. VW Golf, especially some of earlier GTI had this problem.

You talk about ABS and RPM sensor as if they are different things, but they are one and the same I believe. An ABS sensor measures the rotation speed (technically rotation angle) thus speed of the respective wheel.

I always find Mercedes has some very confusing terminology for some of its parts.

The part shown in your photograph is officially know as an electric wiring harness. But it an actual ABS sensor with the restive electrical harness and connector moulded on to it.

As you can see on this mercedes part list it is also known as ABS sensor or front speed sensor.

https://www.mercedesbenzstarparts.co...ess-2465403215

Vehicle speed tends to be measure with (a) different sensor, usually mounted somewhere on the output shaft of the transmission. Although on some vehicles with four ABS/Speed sensors sometimes these are used for vehicle speed as well. Some system use both and the speed is a derived measurement from 5 different sensor. Not quite sure why they would make it that complex, but there you are.

Jeroen

[vattyboy]

Originally Posted by Jeroen

Shocking to hear this, relatively simple job took so long. On some cars it can be quite a problem getting these sensors removed as they get very stuck. E.g. VW Golf, especially some of earlier GTI had this problem.

I just called my SA to clear out this perplexity. He conveyed that the rpm sensor and abs sensor are 2 different parts. Between both these, if any part fails then in both cases, the term Mercedes uses to replace it is called Electrical wire Harness. He also conveyed that 95% of the time only the rpm sensor ceases to function and abs sensors are pretty reliable.

[Jeroen]

Originally Posted by vattyboy

I just called my SA to clear out this perplexity. He conveyed that the rpm sensor and abs sensor are 2 different parts. Between both these, if any part fails then in both cases, the term Mercedes uses to replace it is called Electrical wire Harness. He also conveyed that 95% of the time only the rpm sensor ceases to function and abs sensors are pretty reliable.

Well, the most important part is your car is running fine again. I am a bit curious because the only difference I am aware of is that the front and rear axle use different type of sensor. But they are called ABS sensor by most suppliers.

Have a look at this website. Your speed sensor is listed here as well, exact same number, but it is called an ABS sensor.

https://www.euspares.co.uk/parts-cat...-cdi-d-156-908

Or try this: Just google "Mercedes-Benz CLA200 CD speed sensor” and next google "Mercedes-Benz CLA200 CD ABS sensor” You will get the same sensor, albeit different ones for front and rear axle.

So just curious what your SA is eluding too. Maybe ask him for the part number of what he believes the ABS sensor is. There is simply no difference between a speed - and ABS sensor, although they do come in a variety of versions of course. Any ABS sensor measures wheel speed, that is just how it works, and you need four of them (well on most cars, and front and rear can be different version. Usually because they are mounted in or near the calliper mount and rear is always a bit smaller, less room.

Maybe Indian Mercedes have something I am not aware of?

The same sensor signal is fed into the various computers (e.g. ECU, PCM, BCM etc) and used by different systems for various things, such as throttle response, ABS, ESP, even vehicle speed sometimes.

Enjoy your Merc, nice car.

Jeroen

[vattyboy]

Originally Posted by Jeroen

Well, the most important part is your car is running fine again. I am a bit curious because the only difference I am aware of is that the front and rear axle use different type of sensor. But they are called ABS sensor by most suppliers.

Yeah, you are correct.
Mercedes sales advisers are deficient technically.
Before going to ASS, I called multiple dealerships, and all their SA were confused between rpm/ abs/ wheel speed sensor.

Yes, the front axle and rear axle sensors were different when I got my rear axle left wheel speed sensor replaced, and it was different from this one. It was small and costly. It cost me 11k approx.

[siren373]

On a different note, my advisor asked me to get the wiper on my GLA changed during service. The cost? 8,000. I think I'll go for a Bosch 24 inch blade that costs 1000 bucks.

[bordeaux]

Originally Posted by vattyboy

Speaking about the overall experience of the ASS, I found their work very lazy. I reached ASS at sharp 10 am and they took nearly 6 hrs to complete this small job.

Wow! 6 hours for such a straightforward repair that they must have done umpteen times already as pointed by fellow members in the comments I guess they were trying to justify the INR 2500 for the labor?

[revsperminute]

Originally Posted by vattyboy

Speaking about the overall experience of the ASS, I found their work very lazy. I reached ASS at sharp 10 am and they took nearly 6 hrs to complete this small job.

I assume your CLA is out of warranty. Suggest you find a good Euro Specialist to carry out small repairs/replacements like this. Sometimes ASS will end up replacing parts unnecessarily. A few months back, my Octavia lit up like a Christmas tree. Skoda wanted to replace my ABS module and several other parts for a six-figure sum whereas my independent garage just cleaned some connectors and put them back together for Rs1500.

Coming to the wheel speed sensor, not a big deal. I've ended up replacing 3 out of 4 in my GLE. All under warranty thank god.

[vattyboy]

Originally Posted by siren373

On a different note, my advisor asked me to get the wiper on my GLA changed during service. The cost? 8,000. I think I'll go for a Bosch 24 inch blade that costs 1000 bucks.

IMHO go for the OEM wiper blades their rubber quality is fantastic, very premium, and soft. Bosch aero twin rubber quality is that good, their rubber is hard, and many bhpians have pointed out that they make harsh noise during wiping.
Bosch wipers will not last as much as OEMs, many
bhpians have to change bosch wipers every year whereas OEMs will last much longer( upto 3 years ). My car is still on stock wipers.

Originally Posted by bordeaux

Wow! 6 hours for such a straightforward repair that they must have done umpteen times already as pointed by fellow members in the comments I guess they were trying to justify the INR 2500 for the labor?

I reached the service center at 10 am. And all the staff was just relaxing and chilling out with their morning tea. Till 11 am no work was initiated in any car. After that, there was a meeting for 45 minutes. Work started at 11.45 am. For a simple obd scan, they took 1 hour and 15 minutes, from 1 pm to 2 pm lunchtime.
Started work again from 2.15 pm to 3.15 pm and another 45 minutes for bill and payment.
From this whole incident, it is clear to me that if I take my car to the ASS for small issues or big problems, my whole day will pass there.

Originally Posted by revsperminute

I assume your CLA is out of warranty. Suggest you find a good Euro Specialist to carry out small repairs/replacements like this. Sometimes ASS will end up replacing parts unnecessarily. A few months back, my Octavia lit up like a Christmas tree. Skoda wanted to replace my ABS module and several other parts for a six-figure sum whereas my independent garage just cleaned some connectors and put them back together for Rs1500.

Coming to the wheel speed sensor, not a big deal. I've ended up replacing 3 out of 4 in my GLE. All under warranty thank god.

Thank you for the recommendation.
I always take my car to ASS, I hesitate to take it to FNGs. There is one good fng in my city and once I took their quotation randomly for the 15k scheduled service and I found a nominal difference between them and Mercedes. They charge approx 80% of the money Mercedes charges.
At the Mercedes ASS also I told SA that first clean the sensor and fit it again after that took my car for a short trial but again that warning came out. At last, there was no choice left rather than to replace the sensor.

I am happy to hear that your sensors were replaced under warranty, in my car 2 sensors failed till now and both failed after the warranty was over

[bordeaux]

Originally Posted by vattyboy

I reached the service center at 10 am. And all the staff was just relaxing and chilling out with their morning tea. Till 11 am no work was initiated in any car. After that, there was a meeting for 45 minutes. Work started at 11.45 am. For a simple obd scan, they took 1 hour and 15 minutes, from 1 pm to 2 pm lunchtime.
Started work again from 2.15 pm to 3.15 pm and another 45 minutes for bill and payment.
From this whole incident, it is clear to me that if I take my car to the ASS for small issues or big problems, my whole day will pass there.

I had a similar experience at BMW service center here in Hyderabad. Not sure what's wrong with these people! The mass market players are much better than them at servicing/repairing cars. The only delays there are because they have too many cars to service/repair not because of the high tea session

https://www.team-bhp.com/forum/india...ml#post5415163 (Awful experience @ BMW service center, Hyderabad)

[inline3]

Recently got hit with the same issue in October when it was raining cats and dogs in Bangalore.

The CLA 200 was bought in 2016 and been rock solid reliability wise for the last 60,000km.
Primarily my mother's ride, which she uses to commute to school and back. An everyday run of about 33km.

Got the same errors on the dash on her way back. With the steering/brakes losing assist, it felt a bit agricultural but surprisingly never felt difficult to manoeuvre. No shutting down on the side of the road either.

Straight to the Dealer (Sundaram Bangalore) and diagnosed with faulty speed sensors.

Dealer covered it under Goodwill. I only paid for the labour.

[Vasanth]

Hello there another CLA owner
We too have a Mercedes CLA. In the same Jupiter Red shade. Glad to see you here.
It’s 6th year running. Will be 7 years of ownership in another 4 months.
We have had this very same issue every year without fail.
One of the abs sensor fails, showing the same symptoms. And it was replaced for free which was under warranty. The sensor itself has 1 year warranty. The customer service might vary from dealerships.
It has affected not just CLA models, even A class, B class, & GLA class all over the world.

The last time it was occurred to us was in May 2022 in Pune. And all 4 sensors were replaced free of cost. Also they even mentioned it’s a *modified sensor* which will not fail again. Mercedes will not uncover their faulty ABS sensor to their customers.

I enquired about this issue to my local FNG, he said it’s the issue with the wiring harness with the car itself, not the sensor. He owns a luxury car garage. He services everything from German stable. He too have replaced the sensors for CLA and other models with both OEM as well as other German made sensors. And apparently most customers have come back within 1-2 years with failed ABS sensor.

Do find yourself a trusty FNG who focuses on European made cars, do not hesitate to visit.