lozzd

And every time you touch the brakes even lightly during that time, it's draining your finite power from your ABS module. Replace it now before you have a £3k+ bill

Yeah, that's what happens once this sensor is in this mode. That's the ABS unit kicking in unneccessarily and assisting breaking because it doesn't know the pressure being applied, so goes in to a failsafe. It's good you took it in ASAP as if you keep doing that, eventually it wears out the ABS unit and it requires replacing, costing thousands (it only has a limited amount of use). As others have pointed out, it's a simple sensor replacement, 20 min job and a relatively cheap part.

Either that or get in writing that the garage says it's fine for you to drive. Then you can bill them for the new ABS unit when you get back to the UK, because you'll be needing one. 🤔

If the error came up once and went away, it will be back. It's only a matter of time. Might as well buy the part now in preparation to replace it 🙂

My wife just pointed out we had a symptom of this for months before this happened - the car would be very intermittent as to whether it started or went in to ignition mode when you pressed the brake pedal and hit the start/stop button. 50/50 it would start. In hindsight now this makes perfect sense... The sensor was starting to misread for those many months and the car didn't think the brake pedal was pushed hard enough to start the entire. It starts every time first time now.

I've also found this interesting page that describes the reason for the ABS module replacement: https://uk.autologic.com/news/technical-top-tip-vag ouch.

If there's one lesson I've learnt here, is read the long form description in the manual immediately when these errors pop up. When they say "continue driving, contact workshop" the manual is much much more clear about what they mean: e.g. you don't have to stop the car immediately - your brakes will still work - but you should continue driving immediately to a garage to have it fixed. e.g. You're depleting your ABS module by driving for weeks on it! I guess this is a downside of the modern cars having text messages on the screen - they've got room to describe something but not fully - so people can misinterpret what it's saying. Back in the day where you just got an icon, you'd be forced to pull over and check the manual. I know I am probably in the minority where I immediately stop and investigate any errors fully in the manual as soon as they appear.

My 2019 Q5 showed this (c11ec04 - brake servo restricted - contact workshop) suddenly last week intermittently, and then permanently this week. Luckily since it's in warranty, I hit the roadside assist button in the car, they showed up and replaced the sensor (5Q0906207A) on the driveway in 40 minutes. Fantastic service to be able to get it fixed so fast and easily, and luckily for me I'm in warranty, but isn't it funny they happen to carry a stock of that part on their vans? 🤔 As a data point, we've been driving the car fairly regularly (few times a week and just been on a long 500+ mile round trip a few weeks back) so it's not pandemic idle-ness for us.