New Member - C5 110bhp HDI - Anti Pollution

[Shady]

2004 model just acquired and have had Anti Pollution warning along with the service and engine management symbol on.

May have been an own goal as I put Millars diesel clean additive to a full tank of fuel however, also have following symptoms:

Car will not rev past about 2,800 rpm althouth drives fine otherwise.
The Anti Pollution warning along with the service and engine management symbol went out of their own accord on Sunday afternoon and also yesterday afternoon - 3 stop/starts and remained off - it was quite pleasant and car was well warmed up. Car also ran well up the rev range (i.e. not limited to 2,800). This morning on starting the warnings are back on and revs once again limited - is it temperature related - coolant temp gauge is reading about half way so that seems OK.

Mechanic at local garage loaned my son-in-law a diagnostic tester (not sure which make) and on plugging in fault code P0903 came up along with "clutch actuator circuit high"?

Any thoughts appreciated

[CitroJim]

Welcome Shady...

I believe you'll find this is a symptom of the brake light switch (not anything to do with the clutch!) sending a signal to the engine ECU to say the brake lights are stuck on.

This is deliberate to prevent driving with the brakes on and seems, from a scan around other forums where this code is reported, quite a common fault... It is illogical to go above idle with brakes on so the ECU guards against this. The ECU is presently in Limp Home mode and hence why your revs are limited.

Check your brake lights are not on permanently...

You may need a session on a Lexia diagnostic to finally nail it and reset the fault. Many members on here have Lexia and one may live nearby..

The reason it flags up a clutch problem is this is a bit of circuitry used if cruise control is installed (I believe).

I moved this thread as Introductions are to say hello and not for fault diagnosis

[citroenxm]

hmmmmmm.. I wonder if the faults are NOT related...

The anti pollution fault could also be pointing towards a NON Working vaccum electro valve that controls the turbo waste gate and exhaust EGR valve.

If the electro valve is not working and controling the Vacuum on the waste gate, it works one of two ways, you get NO turbo at all from an open wastegate, or the waste gate stays closed and full turbo boost goes into the engine and the Boost sensor detects over boost and throws the dummy out.

Does full revs return after the engine is swapped?? Or is it permanetly in Limp mode.

Unfortunally due to all the elctronic gagetry on the C5, and the many possibilites of faults, we could all be guessing and stabbing in the dark at faults. A Lexia diagnostic is the ony way to get a better idea of whats what...

Wheres your Location (In the UK, if you are) you could be near a member who has a Lexia and could give you a hand.

[Shady]

Thanks for replies so far, most welcome. I live in Stirling Scotland.

Full revs came back yesterday afternoon, got up to 80 in 4th however service light and engine management symbol remained on until I had stopped then re-started. On starting the warnings were no longer on.

[shumba]

I had exactly the same symtoms on my c5.It turned out to be a blocked air filter, random warnings came up sometimes a week or so appart ,I understand that a blocked air filter has no code so will show itself in different messages, and will not show on a diagnostic, My filter was so badly blocked that engine would sometimes shut down,And this was not long after a supposed full dealer service, A new £9 air filter made the car run much better and no more problems. Hope this helps.