C4 Picasso Steering Issue

[jordyh]

Hi All,

If possible I'd like an extra eye on an intermittent problem that has niggled my 2014 B78 Picasso for a while, getting to the point of being able to afford the repair and want to make sure I'm not potentially attacking a nut with a sledgehammer or missing something glaringly obvious!

Occasionally, a few times a day at its worst, once in a few weeks at its best, the car will fail the power steering as it is straightening itself up after a corner, only ever low speed and is only ever when doing 90+ degree turns, twists in the road are fine, a quick off/on and it resets the service light and its all good again for a while. The steering itself is variable in its heaviness, light as anything when its just happened, to heavy to the point you feel every tooth land in the rack and can pick them out individually, usually an on/off recovers it from that too. Battery is in its first year (was swapped as a stage one in sorting out an ABS fault) so its not likely to be that in my opinion. One thing to note that when its had a long motorway run it calms down and even stop/start kicks in! Local stuff seems to hurt it which is what it usually does.

My topdon code reader throws the following at me; one probably not related!

VIN: VF7**************[VIN obfuscated, can be read by forum staff]
2014 C4 Picasso 1.6 e-HDi Airdream Executive+ 6EGS

Engine:
U1318 Intersystems CAN. Error In Length Or Prohibited Value On The BSI Datastream (Intermittent)

Power Steering
P0606 Fault Inside ECU. Not Categorised (Intermittent)
U131D Fault: No Communication With Parking Assistance ECU. Not Categorised (Permanent Fault)

None of the faults clear on a reset through the code reader so they're not that intermittent!

Any/all suggestions appreciated before I go looking to unload my wallet on someone's workbench!

Cheers in advance.

[GiveMeABreak]

Here are the fault descriptors so you can see the possible causes.

The issue with lack of assistance is listed as a symptom of the faults. All the systems are linked via the CAN network, so an issue somewhere along the line will impact on other equipment that relies on certain data to work.

Fault Code:	P0606
Description of Fault:	ECU internal fault. Possibility 1 - Presence of a short-circuit internal to the Electric Power Steering motor - The time for recording the fault code is 100 milliseconds Possibility 2 - Power steering ECU internal fault - The time for recording the fault code is 15 milliseconds Possibility 3 - Detection of a difference between the supply voltage and the voltage at the terminals of the electric power steering motor - The time for recording the fault code is 90 milliseconds Possibility 4 - The engine temperature must be between - 41°C and 178°C - The time for recording the fault code is 3500 milliseconds Possibility 5 - The operating temperature of the electric power steering motor is too high - The time for recording the fault code is 1000 milliseconds Possibility 6 - Current higher than 10 A - Engine speed less than 30 rpm - Resistance higher than 5 ohms - The time for recording the fault code is 100 milliseconds Possibility 7 - Failure reading and writing to the memory of the electric power steering ECU - The time for recording the fault code is 5 milliseconds Possibility 8 - Incorrect configuration value - The time for recording the fault code is 5 milliseconds
Conditions for Fault to clear:	Ignition switched off and on again
Downgrade Modes whilst Fault is active:	Cutting off of the steering assistance. Lighting of the power steering warning lamp.
Symptoms:	Steering stiff No steering assistance Loss of power steering Assistance intermittent Self-turning of the power steering Steering jammed Jolts in the steering wheel Steering too soft Effect on the dynamic stability control Noise and/or vibration from the electric power steering
Suspect Areas:	Electric power steering ECU CAN network Connector Electrical harness Toothed wheel Coupling of the electric power steering motor

Fault Code:	U1318
Description of Fault:	Absence of communication fault with the built-in Systems Interface: Value received incorrect. Information not received or too short on the CAN. The time for recording the fault code is 500 milliseconds.
Conditions for Fault to clear:	Ignition switched off and on again.
Downgrade Modes whilst Fault is active:
Symptoms:	Semi-automatic parking assistance function not valid Switch from Stop and Start mode to normal mode
Suspect Areas:	CAN network Connector Electrical harness Built-in systems interface

Fault Code:	U131D
Description of Fault:	No communication with parking assistance ECU. Information not received on the CAN. The time for recording the fault code is 500 milliseconds
Conditions for Fault to clear:	Ignition switched off and on again
Downgrade Modes whilst Fault is active:	Semi-automatic parking assistance function not valid
Symptoms:	Loss of the semi-automatic parking assistance function
Suspect Areas:	CAN network Connector Electrical harness Parking assistance ECU

[jordyh]

Thanks Marc,

Clearly its the P0606 fault that's the main issue, how likely is it not to be a fault of the ECU and a fault of the wiring to/from the ECU? If it is the ECU; it's a full rack replace if i've read it right? Would a second hand one be a bolt on job or is it one of those parts that would need coding to the car?

[GiveMeABreak]

Yes, if it's the power steering ECU then it's generally an all in one replacement. Also bear in mind that any replacement will also require tracking / alignment to be done.

I'd certainly be checking wiring connections - especially if any work has recently been carried out as something could easily of been disturbed. The symptoms you describe do see to indicate the steering ECU, but it would need confirmation to be honest. Also, very important to check the part number as there a few different variations depending on engine.