2014 W246 B Class - ESP Inoperative / Pre-Safe Functions Limited

[ssldn]

Evening all - these messages just cane up on my 2014 B Class W246 B180.

It has happened twice previously, maye once 12 months ago and again 1 month ago. Both times it disappeared upon restart.

Some old threads suggest it could be down to the battery being low, is that still an issue on these models?

Any advice is much appreciated, thanks!

 

[AMGeed]

Always get the battery fully charged to see if the error messages disappear for good.
Then you can rule out a battery problem.
The lack of use is slowly running these batteries down as the alarm is still using battery power constantly.

ESP faults often point to a faulty wheel speed sensor. You need Star diagnostics to confirm, and which one.

 

[ssldn]

Thanks AMGeed, much appreciated!

 

[ssldn]

Update ...

I have changed the battery, and replaced a wheel speed sensor which was flagged on Foxwell diagnostics and physically damaged

Unfortunately the car went into limp mode and displayed the same message again today. Another Foxwell scan showed the error below.

Some searching showed these two articles;
- U0415 – Invalid data received – anti-lock brake system (ABS) control module – TroubleCodes.net
- https://static.nhtsa.gov/odi/tsbs/2014/MC-10165847-9999.pdf

The second one is particularly interesting, is anyone familiar with the NHTSA in the US? (I am in the UK btw). A few articles on there link to this fault, and it seems to be a wide spread issue.

 

[markjay]

You changed a wheel sensor, and you are now getting two error messages relating to ABS and traction system....?

New sensor is faulty, or incorrectly fitted, or connector issue, or damaged wiring.... etc.

That's assuming that you have erased the codes and they came back.

 

[ssldn]

Thanks markjay.

The issue is actually that I changed a wheel sensor, and I am still getting the error messages relating to ABS and traction system.

Despite the sensor being clearly damaged (it had snapped). The NHTSA link suggests that the issue could be with a wiring loom further down the chain. I just wondered whether anyone could better interpret the NHTSA doc.

I've not had great experiences with main dealers, so want to make sure I'm well informed before engaging.

 

[markjay]

You only mention that particular error code after you mention the sensor change.

I think that the error codes you got after replacing the wheel sensor are different to those you got before?

You may have inadvertantly created a new problem while fixing the old one.

 

[ssldn]

Thanks to some old articles on this forum I've found Stevenson Mercedes in Maidstone and booked it in for next week. I'll report back

 

[Inodjon]

Evening all - these messages just cane up on my 2014 B Class W246 B180.

It has happened twice previously, maye once 12 months ago and again 1 month ago. Both times it disappeared upon restart.

Some old threads suggest it could be down to the battery being low, is that still an issue on these models?

Any advice is much appreciated, thanks!


View attachment 96372View attachment 96373

I was having a problem with my B-Class (W246) of “pre-safe limited” as well as plethora of other issues on a dashboard, such as ABS lights, parking break, run flat tire inoperative, etc. Even the steering wheel became stiff and gearbox (automoatic) became inactive. I used Icarsoft MB 3, and it threw about 20 or so issues. One thing that drew my attention in error code was “The CAN line has an open circuit”. This was a clue that made me search internet and I found the following solution (also attached just in case):

https://static.nhtsa.gov/odi/tsbs/2014/MC-10165847-9999.pdf

Basically, it says that one should look at left sidewall in front passenger footwell (left hand drive car) and it gives a photo where to look at. And apparently, this is an issue that many cars have too. There, one should check harness, by opening the car mat, and you will see all sorts of cables there. So, I did as instruction in that PDF attachment, and opened the front passenger footwell (left side) and saw a white connection point (its buried in that foamy stuff). I opened that white connection point by sliding a slider back and then reconnected it. I also opened and reconnected other harnesses in the passenger footwell, just below the fusebox. And, VOILA! The problem was solved. No more single errors and no more pre-safe limited issues!

My theory why this could be a potential weakness in harness, is that when one changes the air filter in the passenger footwell, he may end up pushing the carpet so hard back into its place that it might pull the wires in that area and weaken the connections!

I really hope that this information could be of any use to those in troubleshooting, before shelling out on expensive repairs!

 

[Danutlipan]

Thanks to some old articles on this forum I've found Stevenson Mercedes in Maidstone and booked it in for next week. I'll report back

Hi, I got same problem with similar Mercedes’ now, how did you worked it out? Might be same car

 

[Dwesmith]

After 18 months of having an intermittent (but persistent) issue of the Pre-Safe mode coming on, I’ve finally sorted it.

Over this time I’ve taken it to a Bosch engine management specialist, have replaced the battery (which fixed it for around 6 months) but it has kept coming back.

The issue is due to the ECU pin connectors (known fault, too small). The fix which has worked 100%, has been to remove the ECU connectors (located between the battery and the engine), of which there are three (remove two Torx bolts for access under the cover), and ensure all pins make and female are clean, then spray a small amount of AC50 into each female connector port, wipe off any reside, reconnect everything and reassemble. Zero issues now!

Hope this helps.