ABS/ESP pre-safe inoperative intermittent fault W204 C63

[Sheppo-diddly]

Hi everyone,

new to the forum and wondering if anyone can help with a strange intermittent fault i have.

during every journey i get a warning on the dash " ABS/ESP and pre-safe inoperative" sometimes it will disable the power steering and sometimes not. i scanned the car and found a rear left abs sensor fault - this was changed but the fault is still occurring without this error code coming back.

i now get a few different codes and from what i have been told i now have an issue on one or both of the front sensors? sometimes the fault appears when 1st turning the car on, other times after driving for a few miles. it also ALWAYS faults when turning the car back on after a short drive, i.e at a petrol station. even though it got there without fault..



my plan was to replace a front abs sensor at a time. initially i thought it was the module and have since opened that up and soldered all the connections but this didnt change anything.

help appreciated!

thanks

Adam

 

[colinallcars]

Hi everyone,

new to the forum and wondering if anyone can help with a strange intermittent fault i have.

during every journey i get a warning on the dash " ABS/ESP and pre-safe inoperative" sometimes it will disable the power steering and sometimes not. i scanned the car and found a rear left abs sensor fault - this was changed but the fault is still occurring without this error code coming back.

i now get a few different codes and from what i have been told i now have an issue on one or both of the front sensors? sometimes the fault appears when 1st turning the car on, other times after driving for a few miles. it also ALWAYS faults when turning the car back on after a short drive, i.e at a petrol station. even though it got there without fault..

View attachment 142526

my plan was to replace a front abs sensor at a time. initially i thought it was the module and have since opened that up and soldered all the connections but this didnt change anything.

help appreciated!

thanks

Adam

Remember to check the reluctor rings if it has them. Later models use magnets in the wheel bearing’s instead.

 

[OneForTheRoad]

Is your main battery fully charged ?

Also most canbus faults seem to appear above 10mph when the car begins to calculate.

 

[Sheppo-diddly]

Remember to check the reluctor rings if it has them. Later models use magnets in the wheel bearing’s instead.

what is the method to check them? i removed the sensors last night and while looking in the hold rotated the disc. looked clean and non-corroded?

 

[Sheppo-diddly]

Is your main battery fully charged ?

Also most canbus faults seem to appear above 10mph when the car begins to calculate.

i can drive for miles and waaaaay above 10mph before it happens.. does that rule it out? ive heard about battery but seems ok - i.e i left it for well over 2 weeks and it started fine, didn't seem to struggle either..

 

[colinallcars]

what is the method to check them? i removed the sensors last night and while looking in the hold rotated the disc. looked clean and non-corroded?

All you can really do is check that they are secure and rust free.

 

[OneForTheRoad]

Is your main battery fully charged ?

Also most canbus faults seem to appear above 10mph when the car begins to calculate.

Did the fronts show up before you took a soldering iron to the module ? Or just the rear abs sensor. The module you soldered being the abs pump I gather ?

 

[Sheppo-diddly]

Did the fronts show up before you took a soldering iron to the module ? Or just the rear abs sensor. The module you soldered being the abs pump I gather ?

no there was another load of faults before that

 

[Sheppo-diddly]

no there was another load of faults before that

 

[OneForTheRoad]

View attachment 142545

All electrical faults mainly . Get the main battery on charge . If the dash says around 11.7v , it's possibly seeing low voltage. Won't cost you anything to try.

 

[Sheppo-diddly]

12.0v at rest, 14 ish when on..

 

[Sheppo-diddly]

So typically on the way home, all fine, even driving a bit hard and spinning wheels to engage ESP, working as expected then a few minutes later straight line, steady speed and BONG, warning appears again. ? Picking up an ABS sensor tomorow

 

[OneForTheRoad]

So typically on the way home, all fine, even driving a bit hard and spinning wheels to engage ESP, working as expected then a few minutes later straight line, steady speed and BONG, warning appears again. ? Picking up an ABS sensor tomorow

The canbus will intermittently lose signal for a few seconds when the abs sensor can't read wheel speed at the corner, chances are it will be pattern forming at that set speed everytime if you take notice. 12v isn't ideal for the safety systems either , 12.4 to 12.7 is ideal. Your battery is at best 60% charged.

 

[Sheppo-diddly]

So do you think I need a new battery?

 

[OneForTheRoad]

So do you think I need a new battery?

Try charging it . Go from there . I also noticed your steering angle sensor flagged a fault , also caused by low voltage. This in turn causes abs errors , a fully charged battery and turn steering lock to lock 4 times ,will reteach the steering angle.

 

[Sheppo-diddly]

update:

battery charge didn't help things. local garage scanned car and could not access the abs unit. suspect that the abs module is faulty. Mercedes specialist looking at the car on the 10th july to diagnose, if he agrees we will send the module of for repair.

tried new abs sensor but fault was permenent so must be faulty (had this on the rear sensor also - seems only genuine seem to work..)

will update then!

 

[OneForTheRoad]

update:

battery charge didn't help things. local garage scanned car and could not access the abs unit. suspect that the abs module is faulty. Mercedes specialist looking at the car on the 10th july to diagnose, if he agrees we will send the module of for repair.

tried new abs sensor but fault was permenent so must be faulty (had this on the rear sensor also - seems only genuine seem to work..)

will update then!

Abs unit won't talk to the scanner with active faults , it's like it's not even there . When my e350 had issues like yours ,some numpty must of removed my abs unit to do work on the car ,I suspect a replacement headlight ?? and had left the main earth wire loose. I was getting faults intermittently for weeks until one day I spotted the wire was loose. I had exact faults you are having .

 

[Sheppo-diddly]

when you say main earth do you means the earth connection to the battery? from my recollection the abs module connector is one big socket with no separate earth?

 

[OneForTheRoad]

when you say main earth do you means the earth connection to the battery? from my recollection the abs module connector is one big socket with no separate earth?

No. The module on the side of the abs pump. There's a black/brown earth wire fixed to the inner wing about 12 inches down from that hose on the right. This is my car pictured.

 

[Sheppo-diddly]

OK - i will give that a clean-up later just to be sure