I have experienced intermittent faults with my ABS light coming on on occasions, to the extent of having had the coding read, the sensor (Rear, left side) Replaced and after the fault returned, again replaced the sensor (Under warranty) with what the seller stated as being genuine VW part, yet again. (Three so far).

 

Took the car to a well known VW/Audi specialist and they checked coding, came back with rear, left sensor issue. Replaced it with a genuine one, close to £80 each, drove home but after a mile and a half... ABS light on again!

 

They subsequently checked the codes, continuity tested the wiring, swapped left wheel bearing ( Reluctor ring built in) for right, to see if fault swapped sides, still showing rear left ABS fault. They then say the only other thing is the actual ABS module (Pump) and a genuine one is around £800, plus fitting and coding, etc. A figure of around a grand!

 

Has anyone else had these pumps fail/cause a similar issue, etc or any insight as to if that IS the most likely issue? I am extremely reluctant to swap out a thousand quid's worth of work, to still have the issue remain particularly as by next October, the PITA ULEZ charge will mean changing vehicles anyway! 

 

Just for additional information, I have a 2009, 1.4 diesel Greenline, which has ABS and ESP.

 

 

Two thoughts:

You/the garage say the sensor wiring was tested for continuity, but what about short-circuit to each other or either to chassis?

If it does come to module replacement, consider a secondhand part for much less cash?

in some cases the electronics section can be unbolted from the hydraulic part, which might make partial replacement considerably easier. What part number is your module?

There are places that can perform tests on the ABS block controller including connecting it to loads, but that would mean taking the car off the road for a few days probably.

 

I can sympathise with you, back in the darker days when these Bosch ABS controller had not much in the way of self checking, I had a slightly used 1991 VX Cav GSI 2000 16V 4X4, and while under used car warranty it switched on its ABS light, I booked it in, "front near side sensor faulty", paid my part of the repair supposedly cheaper than "doing it the other way"??? - this was the VX main dealer and seller of this car. Drove 4 yards, ABS light back on, turned round and demanded they sort it next day, handed it it next day, "replaced front off side sensor", same thing, the next day "replaced both rear sensors" - I asked if they could diagnose this system and they absolutely, and I asked if they had been road testing after repair again "absolutely".  The weekend arrived and I unplugged the ABS controller and carried out impedance testing both down the cable and into the ABS controller and also spun each wheel in turn and measured the low voltage output from each sensor, everything pointed to a failed ABS controller ie a failed single channel, so back I went with this info only to be told that they had the diagnostic tools and were fit to use them, the car came back that evening "replaced both front sensors, road tested by workshop foreman and passed", same thing after roughly 400  yards, a bit more than just annoying as this was happening in deepest winter where ABS is quite handy to have!  After contacting the service manager, I got a phone call from the service desk to say that they were ordering in a new  ABS controller and and would contact me when it arrived, a few days later they did make contact, I drove round to the workshop, and waited as I knew where the controller was located, under the passenger side door sill trim, and that was that all sorted after a total of 6 wheel sensor replacements then the expensive ABS controller, I was only ever charged for the single ABS sensor replacement also luckily I worked only a 100 or so yards from that VX dealership!

 

So, 2 years later, the ABS light came on again, this time as it was out of warranty, I handed it in to a proper Bosch workshop, they reported that VX would not have been able to extract any fault codes from that version of Bosch ABS controller, so had just been guessing, also, each time they had removed a sensor they had binned it and its PTFE sleeve so every ABS sensor fitted after that without a PTFE sleeve was a time bomb as its aluminium sleeve/body reacted with the cast steel hub housings and the salts generated forced the ABS sensor casing to implode sort off and short out the windings - nice! 

 

I had reason to re-visit that dealership after it moved sites and ended up chatting to the same service manager who assured me that nothing like that could ever have happened, it must be nice to live in a magic world where you can only do good things.

Wino, I have yet to sort out the part number. I have looked around the net a little and noticed people rebuilding some versions and the place I went to mentioned  they could supply and fit a rebuild or get mine done, I think. That puts the cost closer to £250 for the part so still pricey. 

BBA Reman, based in Kent, state some models unbolt the module from the pump, keeping the whole brake system sealed and the module can then be fixed, so no need to re-code as its the same part. This is ok if its actually the module at fault, not the pump. 

I have seen used units range from about a tenner, to over a thousand and on each, the warranty will be nil or very low! So I think if I can confirm for sure its the module or the pump, I will get a rebuild. With the new lockdown, I hope they could still do it, whilst I have to stop working anyway. 

 

One other thing I have noticed, when the light IS on, the ABS seems to "Pump" A little louder, perhaps and a little sooner then I would expect. I can brake quite lightly, albeit suddenly, and hear and feel the pulsating of what I assume is the modules pistons, pumping away. 

I always thought that any failure detected on the ABS would inhibit its operation for safety reasons,  leaving you with normal braking without any ABS intervention. 

What number is the fault code that's occurring?

Rum4mo, I thought the same until recently where I heard that an ABS light MAY inhibit the system... As opposed to WILL!

 

Wino, I grabbed the paperwork from the repair workshop... 

This is copied from the report. I am unsure how to load it in time to post).

 

 

Address 03; ABS Brakes                  Labels; 6r0-907-37 x-ESP80. c1b

       Part No SW; 6R0 907 379 E        HW; 6R0 907 379 N

       Component;  ESP 8.0 front    H06 0002

       Revision; 0000000          Serial number; 00000000000000

       Coding; 0002383

       Shop (Hash) ; WSC 13765 790 00042

       VCID; 408ECA1A109DC38653-5104

 

1 Fault found;

00290 - ABS Wheel Speed Sensor; Rear Left (G46)

                       008 - Implausible Signal - Intermittent

 

 

Just so you know, I could not find the hash-tag symbol on my Apple keyboard so I put (Hash) where there was a hash-tag symbol... On  the line that starts...      Shop.

Forgive me if this sounds obvious, is there a possibility that one of the rear wheel and tyre combinations is a different size to the other?

Wheels are standard alloys from new... Tyres I am fairly sure are of the same size and make on any given axle. I do usually try to have the same all round but have been known to have matching front, matching rears, rather then fully matched all round. I will double check this again tomorrow though so as to eliminate this. I would like to think the workshop ran there eyes over anything that obvious, though. They must have had each rear wheel off in order to swap over the bearings. I would also like to think they would have spotted any potential damage to the internal sidewalls as they are tricker to see then the outsides.

OH, Additionally, I forgot to mention and the workshop techie knows of the issue but my clutch is quite worn and needs replacing soon. It will slip if pushed harder then normal. I would also think they would have said so, if this could trigger an ABS fault.

19 minutes ago, mrgf said:

OH, Additionally, I forgot to mention and the workshop techie knows of the issue but my clutch is quite worn and needs replacing soon. It will slip if pushed harder then normal. I would also think they would have said so, if this could trigger an ABS fault.

 

No it can't trigger an ABS fault.

 

Just make sure the tyres are all the same size all round.

I have had the same fault code on the front of the other Roomster we have. Lived with it for several months until it cleared itself. Came up after changing bearing, renewed sensor twice. Fault was being caused by the connector, I think it was bad pin connections, worth a check and clean.

Thanks, mpm222. I have had 3 replacement sensors, wheel bearings swapped around and a continuity test but sometimes things go wrong and sometimes they correct themselves too. The connector on the wiring looks clean and the sensor, well after 3 replacements, I think its quite unlikely to be them, even the original one, (Making 4) Was most likely ok. I paid around £200 for the diagnostics and replacement sensor, thinking I may have missed something. Then the workshop looked further as it popped back up again within a few miles of driving. That was when they did the other stuff and suggested the pump.