A207 dash message - 'Front Left Malfunction Consult Workshop' (Passenger Seat Occupancy Sensor)

harrye500

Senior Member
Joined
Feb 21, 2017
Messages
557
Reaction score
457
Location
Cheshire
Your Mercedes
2017 W213 OM654 E220 Estate (the main driver) and 2010 A207 E500 (now 'the Summer Car')
Hello all, wasn't sure which section to post this one, Mods please relocate if ness!

So after a couple of years of trouble free motoring, my A207 threw a fault. Long story short, local indie hooked up to star and fault is connected to the passenger seat occupancy sensor being broken.

The fault shows a written message on dash as above + the airbag light is on.

I have obtained a new seat pad sensor from MB Grangemouth for £46 quid which seems to me a very good price with forum discount. I did read up on an emulator or such like to 'fool' the system that there is no fault (rather than replacing same) - I prefer a fully safe car myself so it must be replaced!

I'm confident to replace the sensor myself this weekend rather than the 4 hours labour quoted. My question is, generally is taking the seat out a real pain? Any general pointers or advice? Looking at the seat, it looks like a pretty std electric seat - unbolt from rails, take out and off the rails and take care re wires etc with putting back a reverse of taking out (taking care with alignment and wires etc), I've done similar in other vehicles before.

My main question is, with the seat out, the seat squab looks like it should be removed seperately to place the new sensor under rhe leather, then the single wire looks to go through to the bottom of the seat and plug in underneath. I'm not sure if one 'peels' back the leather or it is done differently, so any advice is welcome.

It doesn't look to be a real cow of a job though, just requiring time to remove it and put it back in properly.

By all accounts (including pro advice) once replaced, the dash warning and light will auto extinguish once it has done its checks.

I will post something on doing this job too, there is diddly squat on the web generally on doing the job, but it does seem to be a pretty common fault with these sensors.

Thinking back too and rather embarrassingly, I probably caused this myself by kneeling on the seat dead centre to clean the windscreen. The fault started pretty much immediately after that, went away for a week then came back in earnest last week! Less said about that, the better I think!! :oops:

Thanks all.
 

LostKiwi

Senior Member
Joined
Aug 25, 2006
Messages
31,324
Reaction score
21,574
Location
Midlands / Charente-Maritime
Your Mercedes
'93 500SL-32, '01 W210 Estate E240 (RIP), 02 R230 SL500, 04 Smart Roadster Coupe, 11 R350CDi
The dash light will probably need a reset before going out. My 210 did when I fitted an emulator.
 

mattkh

Senior Member
Joined
Aug 2, 2006
Messages
3,157
Reaction score
353
Location
England
Your Mercedes
A160 W168 1999 1.6
........ by kneeling on the seat dead centre to clean the windscreen. The fault started pretty much immediately after that, Thanks all.
You are more likely to have stretched some wire. Is there any way to check the continuity of the wires ?
 
OP
harrye500

harrye500

Senior Member
Joined
Feb 21, 2017
Messages
557
Reaction score
457
Location
Cheshire
Your Mercedes
2017 W213 OM654 E220 Estate (the main driver) and 2010 A207 E500 (now 'the Summer Car')
  • Thread Starter
  • Thread starter
  • #4
Thanks gents, possiby a stretched wire, I think I'll fit the new pad as I've got it anyway and also check all the wires underneath for issues and proper connections while the seat is out. Its a learning exercise if nothing else! I will update accordingly! I'll keep an eye on the dash light Lostkiwi - if it doesn't go out then I think maybe its time to treat myself to that Icarsoft MBii I've been promising myself for ages!! Sound investment I reckon as I'll be keeping the car as long as I can
 
OP
harrye500

harrye500

Senior Member
Joined
Feb 21, 2017
Messages
557
Reaction score
457
Location
Cheshire
Your Mercedes
2017 W213 OM654 E220 Estate (the main driver) and 2010 A207 E500 (now 'the Summer Car')
  • Thread Starter
  • Thread starter
  • #5
Morning all. Well, I replaced the front passenger occupancy sensor last Saturday. I waited a few days to see if the dash light would self extinguish, wishful thinking I know! As Lostkiwi said, it would probably need a reset. It did, so I took the plunge and treated myself to an icarsoft MB V2 :) ! Changing the seat sensor involved removing the seat squab and not the whole seat, just 2 hex screws underneath the squab at the front and lift up, Loosening/ removing a wire clip connected to the underside of the squab and cutting a couple of cable ties connecting wires and disconnecting the wires. Be careful if you do this job, as some of the wires are very short and will snap if you lift the squab without cutting the cable ties. Make sure you have some thin cable ties to resecure the various wires when reassembling, or they will get caught up underneath in due course when adjusting the seat! I have the multi contour seats, my worry was that taking off the air pipes that pump up the various bags would snap the various connectors due to age and brittle plastic. Also, the controls for the MC seat is fixed to the squab with a sacrificial type rivet or solder from what I could see, which I don't have. I chose to not disconnect said pipes or the controller, so I lifted the squab and worked on it rather awkwardly, making sure no tension was applied on the pipes. Replacement of the sensor was a case of unclipping the leather seat facing from under the squab and unclipping the retainer wires that connect the leather panel to the sponge. That is a cow of a job, sore fingers a-plenty! The leather panel is connected via clips which are, in turn, connected to thin wires. Don't pull, or the clips will snap and the leather wont fit snug to the sponge when reassembling! The sensor is placed in between 2 sections of sponge and has a control box which is positioned under via threading it through a hole in the sponge.. I did a few pics with the aim to do a photographic write up, but during the operation, my phone slithered down the drivers side seat and I couldn't get it back easily so I carried on! So it was a successful job, but not without a couple of bleeding fingers. In all it took about 3 hours and the car is now back to working order. I will do a full summary write up if anyone thinks that will help, I would think it will be the same method for W212, W204 etc with similar seat spec. The best part was playing with the new icarsoft MB V2 this weekend! Cleared a few minor historic faults plus the fault caused by the seat sensor. Point of note - the old seat sensor pad had a black burn on the circuits which had burnt through and probably severed the circuit! Worth keeping an eye on those I would say. I think I saved a lot on MB labour costs and also now have a new code reader. Winner I think :D !
 

ajlsl600

Senior Member
Joined
Nov 18, 2013
Messages
9,031
Reaction score
6,029
Location
france
Your Mercedes
clk3202001,sl6002003 with everything regrettably sold ,A class 170cdi auto. NG/TF1800 ML250
Morning all. Well, I replaced the front passenger occupancy sensor last Saturday. I waited a few days to see if the dash light would self extinguish, wishful thinking I know! As Lostkiwi said, it would probably need a reset. It did, so I took the plunge and treated myself to an icarsoft MB V2 :) ! Changing the seat sensor involved removing the seat squab and not the whole seat, just 2 hex screws underneath the squab at the front and lift up, Loosening/ removing a wire clip connected to the underside of the squab and cutting a couple of cable ties connecting wires and disconnecting the wires. Be careful if you do this job, as some of the wires are very short and will snap if you lift the squab without cutting the cable ties. Make sure you have some thin cable ties to resecure the various wires when reassembling, or they will get caught up underneath in due course when adjusting the seat! I have the multi contour seats, my worry was that taking off the air pipes that pump up the various bags would snap the various connectors due to age and brittle plastic. Also, the controls for the MC seat is fixed to the squab with a sacrificial type rivet or solder from what I could see, which I don't have. I chose to not disconnect said pipes or the controller, so I lifted the squab and worked on it rather awkwardly, making sure no tension was applied on the pipes. Replacement of the sensor was a case of unclipping the leather seat facing from under the squab and unclipping the retainer wires that connect the leather panel to the sponge. That is a cow of a job, sore fingers a-plenty! The leather panel is connected via clips which are, in turn, connected to thin wires. Don't pull, or the clips will snap and the leather wont fit snug to the sponge when reassembling! The sensor is placed in between 2 sections of sponge and has a control box which is positioned under via threading it through a hole in the sponge.. I did a few pics with the aim to do a photographic write up, but during the operation, my phone slithered down the drivers side seat and I couldn't get it back easily so I carried on! So it was a successful job, but not without a couple of bleeding fingers. In all it took about 3 hours and the car is now back to working order. I will do a full summary write up if anyone thinks that will help, I would think it will be the same method for W212, W204 etc with similar seat spec. The best part was playing with the new icarsoft MB V2 this weekend! Cleared a few minor historic faults plus the fault caused by the seat sensor. Point of note - the old seat sensor pad had a black burn on the circuits which had burnt through and probably severed the circuit! Worth keeping an eye on those I would say. I think I saved a lot on MB labour costs and also now have a new code reader. Winner I think :D !

well done there ,saved a shilling AND learnt something my Q would be WHY did this thing fail in the first place? if not understood maybe yr46£ is going to suffer the same issue ,hope not. being a well known cynic,i suspect a crap sensor made for £3 and sold for £46 ,but thats just me . hope you never have to think about that sensor again, that would be useful tech ,no ?
 
OP
harrye500

harrye500

Senior Member
Joined
Feb 21, 2017
Messages
557
Reaction score
457
Location
Cheshire
Your Mercedes
2017 W213 OM654 E220 Estate (the main driver) and 2010 A207 E500 (now 'the Summer Car')
  • Thread Starter
  • Thread starter
  • #7
Thanks Ajl, I thought also possibly water had got through the leather facing from cleaning causing a short or damp or the likes, could be many causes I'm sure! Re a cheap part, I noticed the replacement was visibly better quality and felt 'less flimsy' so you're probably right the original part was an accountants version and the replacement possibly is uprated - who can say!! The part number also differed and seemed to be a revision on the old part but physically, it was exactly the same. Yes learned a lot, one thing being that the MB seats are VERY well put together!
 
Top Bottom