Multiple warnings

[Reedie]

My 2019 petrol C5 Aircross reported following warnings all at once:

- abs error
- hill start error
- parking brake error
-ESP error
- engine control system

Garage looked at it and said battery was potential culprit and tested the battery and it failed. They cleared warnings. So I had battery replaced under warranty(was only 18 months old) 2 days later all warnings come back. So I returned to garage they tried replacing the abs sensor and made no difference. They have advised they don’t know what to do and would be wasting my money going any further. So have said I need to go to a Citroen dealer. Problem is there isn’t one nearby.

I wondered if anyone had similar issue so I may point the garage in right direction.

Thanks!

[GiveMeABreak]

A faulty wheel speed sensor will indeed cause these faults as they are all dependent upon the correct data being sent from the wheel sensors to the ESP ECU. A fault with one of the wheel speed sensors will result in these warnings.

The question is did they change the correct sensor and if so, did they actually check the wiring connection from the speed sensor to the main harness?
What actual fault codes were picked up?

[Reedie]

They replaced according to the receipt the abr sensor. They described it as the abs sensor to me. They said the one they replaced didn’t appear faulty.

They showed me briefly the code readings and it mentioned near side speed sensor.

They may have replaced the wrong thing then.

[GiveMeABreak]

Diagnostics will show the front or rear and which side - which is why I asked for the code, so I could confirm which one is reporting the issue.

[Reedie]

Thanks for your help! Unfortunately I don’t have the codes just got a glimpse when they were talking me through it.

Dumb question but is the speed sensor and abs/abr sensor a different thing?

[GiveMeABreak]

No the wheel speed sensors can be referred to as the ABS wheel sensors or ESP wheel sensors, but essentially they are the same thing. A magnetic reluctor ring in the wheel hubs on each wheel has a number of alternating North / South magnetic poles, which are picked up by the sensor as the wheels rotate and is sent to the ABS or ESP ECU to determine the individual speed of each wheel.

Because the ESP system uses this data in conjunction with the steering wheel angle sensor and other sensors on the vehicle for trajectory correction, over / under steer, aquaplaning, traction control etc., it has a direct impact on the road holding features like the Hill Start Assist and electronic parking brake as well as the obvious ABS and ESP functions.