Another A-Class (A140 W168) BAS/ESP problem but with many variables...


New Member
Jun 10, 2013
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Southampton, England
Your Mercedes
A140 (W168) - 1999/V - Petrol - ACS
Right so you are all probably licking your lips hoping to know the solution to my problem and so far I haven't done much of the typical fixes such as break sensor etc. but my version of events go like this:

Feb 2013 - Purchase the car. Within a week = poor engine revs, stuttering, spluttering, high idle, poor acceleration, impossible to drop a gear and over take etc. *SOLUTION* > Take it back to forecourt and get adjoining garage to look at it. They tell me about the gunk build up etc. so I insist that they remove the ECU/MAFS box, throttle body and connecting pipe. Considerable amount of yellow gunk was present and throttle body and pipe received a thorough clean. Perfect! £1000+ ECU/MAFS did not need doing!

May 2013 - Minor experiences of previous problem, nothing to worry about, just keep petrol above half a tank and use Shell V Power fuel (personal preference but its very clean and helpful to engine etc. steer clear of supermarket forecourts) *Crash* some idiot drives into the side of me near home(Cat C right off - just 2 doors luckily nothing structurally wrong at all!)

June 2013 - Long 200+ mile journey, fuel running low. Next day slightly poor idle revs. I clean throttle body myself (after watching mech. do it I realised it was only 7 screws) but forget to replace the sensor cable (didn't notice straight away) that goes into it. Car reacts negatively to this: terrible idle revving which cannot maintain a constant, popping sound near engine, engine sounds as if air and fuel not mixing well, car shakes with engine trouble [turns engine off]. Attempts restart to 'flush' through what I thought was a minor build up of air/fuel due to my mistake but no start what so ever! I look at engine bay again and retrace my steps to then discover my error with the lead so I reconnect it to the throttle body. Car restarts but with BAS/ESP sign. I take it to petrol station for refuelling (as it was still low by this point) again to hopefully flush the system through to get an even mixture of air and fuel again. On way to p/station the dash illuminates with various symbols and the car goes into fault mode (gear 3 changed to F) which renders the car useless, all engine power and gear functions disappear and the engine revs, when throttled, as if not in gear. A couple of minutes later, after waiting embarrassingly stuck at the junction 100ft from p/station because it would not start, it restarts! for the next day I still had some 'fault' problems but they seemed to wear off as I 'expected' after reconnecting said cable. I make the return journey home problem free! However over the course of two weeks the 'fault/F' problem returns, irregularly midway through various journeys by which I can turn engine off and on again and it works but it progressively gets worse to the point where I woke up the other morning and the 'fault/F' was there the moment I turned the engine on! 10 miles later the car 'faults/F' and after turning engine off I have lost all power this time. I tried jump starting it and still no power not even ticking over in anyway, yet the dash was still like blackpool illuminations. :confused: therefore the battery still had power which mooted my alternator theory. I went back that evening and after a few tries the engine starts without too much bother (low stuttering revs, followed by automatic 3000 rev choke then settles gently to 800 revs or so) so I drive it safely home less than a mile away.
RAC are called for home start and he seemed to think there was an excess amount of fuel being consumed based on fuel smell in cabin and eggy smell outside. I brief him on the history and he thinks there are probably some fault codes either related to my error with the cable or even more likely (which I never considered at all due to the low damage) was the side impact crash had caused some computer problems.
I returned to the initial garage that cleaned the gunk and the hooked it up to the computer, gratis, and there was a whole host of problems! ECU, ABS, BAS, ESP etc. he cleared these faults, revved the hell out of the engine and seemed to flush a bit more cr@p clear, retested the computer twice and ZERO faults on his laptop!

I am currently driving the car 2 days later and have not had one fault! should I expect a fault in up and coming days/weeks or does anyone think this is now cleared and both the crash and my human error caused rectifiable computer faults?!

(oh and when the car failed to start each time after faulting I believe that was due to engine flooding with too high a fuel mixture due to computer telling it to send more lol, good cut out feature. I'm also aware that I am very lucky for my mechanic to do that computer diagnosis and repair for free :p)

[sorry for the large essay but I always read that people omit information in the original post, so hopefully I have covered all bases here lol :D ]

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