C4 Picasso 2013 ABS/sensor error

[polophonic2025]

Greetings all, I hope someone will be able to help me with what seems to be a rear speed sensor problem.

A few weeks ago the dashboard on my 2013 C4 Picasso Exclusive lit up like a Christmas tree, lots of alarms, stability control off, tyre pressure cruise off, ECO off etc. This followed some intermittent faults and warnings that quickly resolved themselves. Reading the codes produced a bunch related to Right Real Wheel Speed Sensor:

C003A(01)/(95)/(11)/(96)/(2F)
U1213
C1391(00)

I have searched this forum and found many posts related to the rear wheel speed sensor & ABS, and in particular the wiring. I jumped in and did indeed find suspicious wiring to the sensor that included rubbed away insulation and kinks. I ended replacing as much of the yellow & green wires to the sensor that I could. I also replaced the sensor.

Alas, errors persist and I still get warnings & alarms the moment I turn the car on. I have booked the car into the local dealers for Friday as I think this is the only garage that is going to have the appropriate diagnostic kit and get get to the bottom of this.

I would be very grateful if anyone could help me avoid the £150 it’s going to cost me just to have the dealer tell me what they think the problem is - before quoting me what’s likely going to be a pretty outrageous amount to fix it!

[mickthemaverick]

Have you cleaned the ABS ring and checked it is not corroded and running true?

[RichardW]

They're all circuit faults, and if the warning dings as soon as you open the door then it's fussing about the circuit integrity not a poor reading.... Odds on it's a fault in the wiring, you just haven't found the bit yet - it can be right up over the axle - I wouldn't waste money at the dealer they will just tell you it needs a new harness at ££££lots! Sometimes the wire breaks right at the plug - give it a good tug.

[polophonic2025]

Have you cleaned the ABS ring and checked it is not corroded and running true?

I've had a look at the ring and can't see any obvious corrosion. If the errors happen immediately after ignition and/or the car is stationary then I'm thinking it must be some wiring or component issue somewhere...

[polophonic2025]

They're all circuit faults, and if the warning dings as soon as you open the door then it's fussing about the circuit integrity not a poor reading.... Odds on it's a fault in the wiring, you just haven't found the bit yet - it can be right up over the axle - I wouldn't waste money at the dealer they will just tell you it needs a new harness at ££££lots! Sometimes the wire breaks right at the plug - give it a good tug.

This is what I sort of fear! I can't imagine what they would quote for a new harness.

I replaced as much of the wire as I could - right up to the plug and did some resistance testing and it *seemed* to be good. Do you know where I can get a replacement plug from? I can't seem to find them listed. Perhaps it's a generic part?

Is it possible to test the entire circuit? From the plug to, well, somewhere up into some ABS control unit under the bonnet?

[polophonic2025]

FIXED
I jumped back into the job and further checked the loom. Working higher up from the initial wire break, I found a yellow wire break very near where the wiring disappears into the interior. I was just able to strip the wire, tin it and solder it back to the wiring to the sensor. Bit of pig of a job. But if the break had been any further along the loom then I would have had to replaced the entire section.

I'm hoping the solder and heat shrink, with liberal application of insulation tape will hold this together.

Many thanks to all the posters who have detailed this job in the past.

[Paul-R]

Excellent detective work and (hopefully) repair work there.

[polophonic2025]

Excellent detective work and (hopefully) repair work there.

I know where to start when the rear left sensor starts playing up