ABS - for information

[Boxer]

I've just resolved an ABS problem on my daughter's 2009 B9. We were getting a bit of vibration through the brake pedal at low speed, then a full ABS fault light - and a code reader gave a "coherence fault" at the front left brake. After checking electrical connections including continuity from sensor plug to ABS controller plug, buying a new sensor and generally searching about for a cause, I decided to recheck the sensor mounting. What I found was that the area where the sensor sits had been corroding and there was a build up of rust which was preventing the sensor from sitting flat. With a light chisel I gently tapped the material away. I refitted the sensor, now around 0.5 mm closer to the wheel bearing, and it's all good.
I suspect that the slow build up of rust had pushed the sensor (plastic construction held by a single screw) out of position.
As ever - check the simple stuff first! Will I ever learn?

[Satellitemark]

Hi Boxer,

This problem caused me a load of grief, and was found and cured by a Citroen specialist in Swansea.
The corrosion had moved my sensor away from its position and causing error messages, the specialist used Dremel to grind away the corrosion and get the sensor air gap back in spec.

Mark

I've just resolved an ABS problem on my daughter's 2009 B9. We were getting a bit of vibration through the brake pedal at low speed, then a full ABS fault light - and a code reader gave a "coherence fault" at the front left brake. After checking electrical connections including continuity from sensor plug to ABS controller plug, buying a new sensor and generally searching about for a cause, I decided to recheck the sensor mounting. What I found was that the area where the sensor sits had been corroding and there was a build up of rust which was preventing the sensor from sitting flat. With a light chisel I gently tapped the material away. I refitted the sensor, now around 0.5 mm closer to the wheel bearing, and it's all good.
I suspect that the slow build up of rust had pushed the sensor (plastic construction held by a single screw) out of position.
As ever - check the simple stuff first! Will I ever learn?

https://www.berlingoforum.com/showthread...#pid107670

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[jj9]

The problem with rust moving the wheel speed sensor is common on a lot of cars so always worth checking first.

Glad you're sorted.


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