2009 C4 Grand Picasso ABS issues

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HardNock
Posts: 3
Joined: 05 May 2022, 15:32
x 1

2009 C4 Grand Picasso ABS issues

Post by HardNock »

Hey all, I'm new here but have owned Citroen and / or Peugeot cars most of my driving life. I purchased a 2009 C4 Grand Picasso VTR+ 1.6 HDI with a 6 speed semi-automatic gearbox (VIN VF7**************[VIN obfuscated, can be read by forum staff]) in March of this year. Lovely car, very clean for the year. I had no issues with the car until I had a tyre replaced and tracking altered, after which I was getting intermittent issues with an ABS sensor (triggering the usual ABS / EPS / Parking Brake / Gearbox fault messages). DiagBox (and an Autel diagnostic handheld device) both displayed error codes C1 331 Front right wheel speed sensor signal fault and unable to select higher than third gear. Stopping the car, turning off the ignition and starting the car back up then pull off and drive cleared the fault, assuming because the speed sensor was picked back up. This was quite intermittent and only seemed to really occur on longer drives when getting to 50+ MPH. The speed / ABS sensor itself was disgustingly filthy so I cleaned it up but the issue remained. I purchased a new sensor and fitted it, but now the fault is permanent. If I clear the fault and drive off, the same fault re-occurs almost immediately. I removed the new sensor thinking it may be faulty and re-fitted the old sensor, but this also now triggers a permanent fault. I've removed the wheel and cleaned around the whole hub, wheel bearing and driveshaft as they were pretty dirty but the permanent fault remains. I can't drive the car any more as I can't select higher than third gear. When I check live data, there's voltage on each corner so the sensors are being detected by the module. Any ideas? I'm now at a loss! I don't want to believe the ABS unit itself is faulty, it seems too coincidental that the fault only occurred after a tyre change and tracking adjustment (the tyre was o/s rear, so not the same corner as the fault) and the permanent fault only occurred after changing the sensor.
HardNock
Posts: 3
Joined: 05 May 2022, 15:32
x 1

Re: 2009 C4 Grand Picasso ABS issues

Post by HardNock »

So I've checked the 5A fuse and wiring feeding the ABS unit and can't see any corrosion. I've bought a new Active Sensor Bearing (wheel bearing) for the same corner and fitted that, still have the same issue. So frustrating because the car is stuck at my brother in laws garage 30 miles away and I can't even drive it home!
HardNock
Posts: 3
Joined: 05 May 2022, 15:32
x 1

Re: 2009 C4 Grand Picasso ABS issues

Post by HardNock »

I fixed the issue and thought I'd post the solution in case this crops up with someone else. The sensor and active sensor bearing both turned out to be fine and functional, as were the connectors and electric harness. It turned out that the sensor mounting had been knocked slightly out of place somehow. The only work done to that corner was the tracking correction, as mentioned in my original post. I took measurements and compared them with the n/s front corner and the o/s front corner which returns the error differed by a few mm. I manipulated it back into position and the error hasn't returned since.