C5 II ABS/ESP fault after sensor replace

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KarlT
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C5 II ABS/ESP fault after sensor replace

Post by KarlT »

I have a ABS/ESP issue. The front RH wheel sensor is the bad one according to Lexia. I have read that it can be alot of issues that give ABS fault, I changed the sensor but it is still ABS fault. Lexia says that 3 sensor working great, all show the same speed when I drive and 0 km/h when parked but the front RH sensor is stuck at 655 km/h, it was the same with the old sensor. I delete the fault code after the sensor replace, drove the car in 45km/h.

What do you think is the problem?

The car is a Citroen C5 2,2 HDI 2007
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oldbill
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Re: C5 II ABS/ESP fault after sensor replace

Post by oldbill »

Its not unknown for lexia to confuse the sensors across an axle. You could also use a test meter to measure the resistance across each sensor, they should all be the same. Damaged or corroded sensor wiring can also be a problem.
Good luck Bill
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GiveMeABreak
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Re: C5 II ABS/ESP fault after sensor replace

Post by GiveMeABreak »

There are several wiring connections from the wheel speed sensor back to the ESP ECU, so the issue may not be at the wheel speed sensor cable itself, but further up - as it's suggesting a short circuit.
C5 MK II ABS Sensor.png
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Re: C5 II ABS/ESP fault after sensor replace

Post by KarlT »

GiveMeABreak wrote: 28 Jan 2024, 20:00 There are several wiring connections from the wheel speed sensor back to the ESP ECU, so the issue may not be at the wheel speed sensor cable itself, but further up - as it's suggesting a short circuit.

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Thank for the answer! No, unfortunately it wasn't just a broken sensor. I have read about ABS fault problem and all things that can make it appear so I dont know what to start with. I'll start with what you said. I'ts new front wheel bearings so I dont think it's a sensor ring issue.
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Re: C5 II ABS/ESP fault after sensor replace

Post by KarlT »

oldbill wrote: 28 Jan 2024, 19:56 Its not unknown for lexia to confuse the sensors across an axle. You could also use a test meter to measure the resistance across each sensor, they should all be the same. Damaged or corroded sensor wiring can also be a problem.
Good luck Bill
Okay, it's maybe not the sensor that Lexia says. I have measure both front sensors, first time I did it wrong because I used the passive sensor method. I think I did it the right way after I read how active sensors are measured but I will measure again.

Thanks
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GiveMeABreak
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Re: C5 II ABS/ESP fault after sensor replace

Post by GiveMeABreak »

KarlT wrote: 29 Jan 2024, 09:04 Thank for the answer! No, unfortunately it wasn't just a broken sensor. I have read about ABS fault problem and all things that can make it appear so I dont know what to start with. I'll start with what you said. I'ts new front wheel bearings so I dont think it's a sensor ring issue.
I didn't mention a broken sensor. What I said was, it may not be a problem near the sensor itself, but further up the wiring. However, I find that Lexia is usually correct in identifying the correct sensor.

Second, you now mention that the bearing has been replaced, which could indicate that the problem has been with the fitting or the part itself. Too much of a coincidence that the problem has started with the bearing replacement....

1) Is it possible the magnetic ring has been damaged? There are 48 pairs of poles inside and these can easily be damaged if it is dropped or put close to another magnetic source or near anything with metallic particles.
2) Was the bearing face fitted the correct way? The face at 'a' has to be facing the driveshaft as shown below.
c5 mag ring.png
3) Did you fit the correct part for the vehicle that has the magnetic ring fitted? If not, then you won't get any data or a static value.
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KarlT
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Re: C5 II ABS/ESP fault after sensor replace

Post by KarlT »

Yes, both bearings are the correct ones and fitted correct way.
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Re: C5 II ABS/ESP fault after sensor replace

Post by KarlT »

I disconnected the sensor and it shows the same value in Lexia, 655kph.
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Re: C5 II ABS/ESP fault after sensor replace

Post by GiveMeABreak »

That would make sense - no data being received so is defaulting to that value.
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Re: C5 II ABS/ESP fault after sensor replace

Post by KarlT »

Secondary stop lamps switch - Not operated

When I press the brake pedal this shows in Lexia.
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GiveMeABreak
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Re: C5 II ABS/ESP fault after sensor replace

Post by GiveMeABreak »

That is normal behaviour. The twin brake switch has 2 circuits; a make / break function for safety with the cruise control. So when the brake pedal is operated, the secondary switch is released. These should reverse when you release the brake pedal with the main switch saying not operated and the secondary brake switch saying operated.

If they are not reversing their functions as you press and release the brake, then the switch needs replacing.
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KarlT
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Re: C5 II ABS/ESP fault after sensor replace

Post by KarlT »

I will go on trying to solve this. I have worked with my mothers car, a open circuit fault but not on the ABS circuit and not on a Citroen. After checking every part and measuring everything in that circuit I finally found what was wrong and that have give me knowledge of open circuit fault and how to troubleshoot it via electrical diagram, measuring and checking parts in that circuit, so I have high hope that I will solve my ABS issue......
KarlT
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Re: C5 II ABS/ESP fault after sensor replace

Post by KarlT »

I have searched for electrical diagrams to my C5 2007, especially to the ABS/ESP system but I have only found diagrams to the C5 generation after mine.
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GiveMeABreak
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Re: C5 II ABS/ESP fault after sensor replace

Post by GiveMeABreak »

Pop your VIN up and I'll see what I can do. Please post your VIN in full without spaces - it will be automatically masked from public view after submitting your post & will only be visible to staff.
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Re: C5 II ABS/ESP fault after sensor replace

Post by KarlT »

Thanks for the quick reply!

VIN:VF7**************[VIN obfuscated, can be read by forum staff]