VW Golf GTI MKV

Part four: We suspect that the plethora of warning lights is due to an ABS unit fault.

When we bought our GTI MKV from BCA Nottingham, one of the reasons for the cheap purchase price was that it was showing a couple of warning lights. These were an orange EPC light and an orange traction control light. On the drive back home, the EPC light went out, came back, then went out again after cutting the engine and restarting. It didn’t come back on.

The traction control light, however, would not go out and, when we scanned it, we kept coming up with fault code ‘1435 sensor 1 for brake booster G201’ and it would not clear. Golfs of this age are prone to wiring problems, but it was most likely a fault in the ABS unit itself.

The Golf 2.0 FSI and GTI cars have their own ABS block – the ESP type with the part numbers visible on both the plastic ECU and the pump motor body. A good secondhand ABS seemed like the best way forward. A trip to a breakers unearthed the exact same unit on a 2007 SEAT Leon TDI, and another identical one on the Leon next to it. One was original and one was a recon, but at £35 for the pair it was worth a shot.

We’d contacted Roger Bagg at ECU Testing in Heanor (01773 535638) about getting our existing ABS unit fixed, with a plan to fit one of these secondhand units as a stop gap until it came back. However, that didn’t work out.

Bespoke coding

Unlike other makes, where one ABS pump is the same as another and can be easily coded to the car, VAG have made this a nightmare. Each pump is coded to a specific car and needs an option code detailing what wheels, brakes and engine are fitted, as well as whether it’s a threeor five-door model. While swapping the pump and bleeding the brakes wasn’t too hard, the replacement pump would not code to the car, despite Parkside Garage having done these before.

Apparently, you need to clear the codes from the existing ABS ECU back to zero, then enter new codes – each car has an option code on a sticker in the boot and, of course, ours was missing. So we went from a single light showing to a car where the ABS, brake pressure and tyre pressure warning lights were on, accompanied by the most horrendous beeping siren.

On the drive home to Sheffield, the brakes worked fine with the secondhand replacement unit, then the traction light popped up. As ECU Testing is just 45 minutes from Sheffield, we drove there to see what could be done ASAP.

Roger Bagg quickly ran through the system on his laptop and found that while the replacement ABS ECU had been zeroed, there was no way of recoding it to the car, as such. It would never work until it was removed. Despite it being late in the afternoon, Roger got one of his skilled techs to test our original unit and found that the ECU was OK. It was the valve block that was faulty.

Luckily, they had a remanufactured unit in stock and, within half-an-hour, our good ECU was mated to the valve block, then the complete unit tested on a rig. We had to wait a week before Parkside could refit the unit – sure enough, all the lights went out and it’s been fine ever since.

As for the cruise control, that turned out to be a fault in the indicator stalk. Some VAG cars have stalks where the inner switch can be unplugged, but others are hardwired into the stalk. Luckily, ours was the former and, 20 minutes later, cruise control was fully operational.