E55 W211 project - the fun vs frustration balance

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New Member
Aug 1, 2023
Guildford, Surrey, UK
I recently bought a 2003 E55 (RHD) with a number of issues to work through, thankfully some were addresses recently and I've made further progress with a few, but there are still a number of items that I can see will be testing my patience over the coming weeks and months.

Some of the recent items include:
  1. Supercharger tensioner
  2. Aux belt idler pulley
  3. Aux belt tensioner
  4. Drive belt
  5. Bosch water pump for parking heater
  6. Water pump
  7. Fuel filter
  8. Fuel pump relay
  9. PSE Pump
  10. Front cup holder (they seem to enjoy breaking)
  11. Replacement batteries (front and rear)
  12. Battery control module
  13. Alternator regulator
  14. Key fob batteries
  15. Cleaned up the seats
PHOTO-2023-07-30-20-47-20 12.JPG
PHOTO-2023-07-30-20-47-20 13.JPG
Replacement PSE pumpIMG_7032.jpeg

Seat before
Seat after

Items that remain on my project list include:
  1. "Malfunction electrical consumers switched off” error on the dash. All electrics appear to continue working
  2. Boot lid automatic close doesn't work (motor operates:
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  3. Replacing the missing AMG badge from the front driver
  4. Sticky handbrake (doesn't release cleanly)
  5. Boot lid handle sticky (doesn't reset it's position once pressed, but it does function correctly)
  6. Keyless start and entry don't work
  7. Driver side speakers are not working
  8. Rear left airbag seems to have a small leak (it'll drop over the course of a couple of days when left)
  9. Passenger side wing mirror doesn't fold in
  10. Super charger oil change
  11. Gearbox service
It's all going to take time to get right, but the Malfunction error is the main priority at the minute. Having replaced the two batteries, BCM and alternator regulator I'm wondering where to go next. I'm considering the relay and various grounds as the next checks. Voltage is ~14v when running so the system seems to operate correctly. I may also revert to an auto-electrician on this one as it is already testing my patience.

With all this said I am enjoying driving the car, though it is a fun brute.


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It's a fun car to drive but not so fun to own when running costs are steep.
This is a complicated car with special meaning very expensive components.

If you bought it cheap then there was a reason why it was cheap, p/o wanted to get rid of the car.
Well I expect that cheered him up!
.....I'm sure he paid the right price for it knowing at least some of the the issues. Rolling projects have been some of the most fun and best value cars I've owned. Made nearly 5k after two years of use when I bought my A8 4.2 V8 with similar issues. Cheap way into a great car.
I would say it looks like the OP could do well to buy some sort of diagnostic tool. Otherwise it's just parts darts and wasted money until you stumble across the answer.
Thanks for the comments, I don’t mind the heart breaking along with constructive remarks.

I've been using the Foxwell NT530 for diagnosis (with Mercedes module), which seems to work reasonably well but probably lacks some detail compared to Mercedes star.

As far as codes go, there is a list of those too which I have been trying to work through, for completeness here they are:
  • 920C - DCM-FL door control module front left - The output of component M21/1e1 (left outside mirror ambient lamp) has short circuit or open circuit. Code ‘Surround lamp’ is probably wrong.
  • 9261 - TPC tire pressure monitor - Signal transmission between at least one wheel sensor and N88 (TPM control unit) is faulty
  • 9092 - On board electrical system (voltage supply) - Component G1/7 (auxiliary battery) is defective or not installed
  • System diagnosis (CAN) - no response to the request for codes
  • 9063 - ESA driver electric seat adjustment driver - No normalising of head restraint adjustment
  • 9181 - DS-RF right front dynamic seat - Switch S108s1 (right front pulse switch) or S108s3 (right front lumber support adjustment switch) does not open
  • 9182 - DS-RF right front dynamic seat - Switch S108/1 (right front dynamic switch) does not open or has a short circuit
  • 9250 - DSP pneumatic pump for dynamic seat - pressure build-up not possible due to a leak
  • 9254 - DSP pneumatic pump for dynamic seat - pressure relief valve for draining opens without active overpressure run
As for the car, I knew what I was buying and deliberately chose something that required attention. I have other vehicles that I use for more practical purposes, so this E55 AMG was purely added to the driveway for fun (in fixing and driving). I've got my eyes open to the costs, and am not that fussed what it costs me in the end, I enjoy the journey and taking a car and making it a better version of itself.

I've been considering buying the full Mercedes diagnostics kit, but it feels a little overkill for what I need and I'm concerned that it will open doors to places that I don't know how to manage.

This project comes after a Westfield 7, BMW Z4 3.0si & Porsche 911 3.6, all of which have been great fun and different challenges to work on.
I take it you reset all those to see what comes back and what is historic.
If the codes are not permanent, don’t worry about them, it’s just an FYI.

The wing mirror should be a easy fix… broken wires because of the folding in/out.
Looks like a great project and good work so far, I recently bought a similar E55 myself and working through it.

Was this on eBay recently, looks like one I was looking at?
Enjoyed reading this thread... these wonderful cars are worth the time and effort -

1) they effortlessly combine ferocious pace with genuine comfort (something MB have forgotten)
2) they look great, timeless in fact
3) people love them, I am regularly stopped at petrol stations etc for chats with all sorts of petrolheads who love my car
4) you can mod them for even more madness very easily
5) they're now rare and mean you're driving a modern classic with a hard to find cool factor
6) they cost £2-£3k to keep on the road a year, but provide unlimited smiles per miles
7) you can use them as they were intended and no one is fussing about boring stuff like residuals or mileage
8) if you have a wagon you can fit a washing machine and dryer in the back with the seats down

If you know... you know

A genuine Merc/AMG masterpiece

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