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steering and suspension gone hard

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Fri May 22 2020, 05:07pm
Joined: May 21 2020
Member No: #4351
Location: Nelson
Hi all fellow C6ers. I own a C5 III but am desperate for help. I had to replace the lower arm bushes, and when picking the car up from the garage the suspension and the steering had gone quite stiff. The magic carpet ride is gone, as if the car was stuck in Sport mode (I am not sure exactly how Sport mode feels as I never use it); small bumps are felt quite hard. When I do change to Sport I hardly notice any difference. Car height is fine. The front goes down when turned off and it rises with ignition as expected. I have cycled the car though the different positions several times and all works well.

Garage has checked LDS, recalibrated the suspension. Lexia only shows errors regarding the steering angle sensor (U1213, U1205, U2005), ghost codes?. During a recent tyre rotation I asked those guys to have a look: they bled the power steering and suspension system and recalibrated the speed angle sensor with a 30% improvement, but still stiff. They suggested a power steer pressure test? I haven't done this; would it be worth it?. Other tests which I struggle to understand involve the CSS unit, part of the ECU? Some parameters there are off, but the belief is that that unit doesn't fail and it would be mad (and expensive) to replace. Any experience here?

Other random things I've seen since then. When I turn the ignition on especially in the mornings, in the display I see messages about "Child safety activated" and "Automatic door locking activated", which I never used to see before. On one single occasion, and in the middle of the day, the car was in economy mode when I turned the ignition on.

All help appreciated!
1 User said Thank You to dangafo for this Post :
 cruiserphil (25 May 2020)
Fri May 22 2020, 05:49pm

Joined: Oct 01 2009
Member No: #1
Location: Northumberland
U1205 = Fault in the information received by the steering wheel angle
sensor over the CAN network : Value received incorrect / Steering wheel's angle sensor

U1213 = Engine ECU (Internal failures or network communication) ABS/ESP ECU or CAN network

However a common issue when changing suspension bushes is the 'ride height' sensors getting out of alignment usually down to the mounting brackets getting bent but as ever make sure the battery is fully charged as a low charge can cause umpteen issues.
2 User said Thank You to C6Dave for this Post :
 dangafo (22 May 2020) , cruiserphil (25 May 2020)
Fri May 22 2020, 06:01pm
Joined: May 21 2020
Member No: #4351
Location: Nelson
Thanks for your reply. Do you think the height sensors may explain the steering issue as well?
Wed May 27 2020, 05:46pm
Joined: Jan 03 2018
Member No: #3382
Location: South
I've no experience of the C5, but this sounds very similar to the problems I had on the C6. As per C6Dave's comments, incorrect calibration of the wheel travel sensors (including bent brackets) causes much chaos. In my case, non-deterministic chaos that was hard to trace / recreate...

The wheel travel sensor data, I believe, are part of what the suspension controller uses to assess / correct body roll. If the data is poor, then the ECU will complain and likely enter a 'safe' state - causing a stiff ride that restricts travel (one assumes to protect the underbody, as the travel distance can't be calculated due to bad sensor data). In my case this did make the car feel altogether stiffer and at times, a little 'crashy'.

If the steering is heavy (like a loss of power in the assistance system) then that could well be a different problem. I never experienced this with the C6, but I don't know it's set-up on the C5. Whilst bad sensor data will upset the suspension and in turn, the ride - I'm not sure how this would affect the power steering system. I assume this is a hydraulic rather than electrical system (but I don't know) and in which case a heavy action on the wheel suggests a loss of power in the hydraulic circuit (such as through pump failure, flexing high-pressure lines or leaks). Alternatively, if the feeling is stiff rather than heavy then it may well be a consequence of the suspension entering this error state.

I'm not a believer in coincidence and that this only happened after work on the control arms makes me suspicious. Calibrating the sensors properly is a faff (or it was for me at least), but if done methodically and on genuinely level ground is achievable with DiagBox. I feel your frustrations...

There are a lot of Citroen experts on this forum who would know far more than I about the suspension and steering systems on the C5 - please just take this as my two pence.
3 User said Thank You to mixolydian for this Post :
 dangafo (27 May 2020) , cruiserphil (28 May 2020) , kitch (08 December 2020)
Fri May 29 2020, 06:09pm
Joined: May 21 2020
Member No: #4351
Location: Nelson
Thanks to everyone that has taken an interest and come up with ideas. I will be taking the car to another garage, 250km away. But I thought I would give an update. The change of bushes took place in late March. Now it is as if the magic carpet feel is slowly coming back. Or could it be that I am getting used to a stiffer car? I doubt it. The steering seems to be better too. Bizarre.

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