Intermittent high rail pressure.

[centurus2400]

2008 C5 2.0L HDi. 136 hp. Delphi fuel system. 6 speed Aisin-Warner auto. The car is running very well under normal conditions. However, if you really clog it, either by flooring the throttle at 45mph and going into kick down, or travelling at high speed and again flooring it, there is sometimes the dreaded 'Antipollution Fault' coming up, along with the management light. Engine speed then limited to 3000rpm - however, after three starts it all resets and the EML goes out again. The Lexia is showing that this is caused by high rail pressure, which is being logged, but as I said, the fault is intermittent.

A friend of mine, who is a very clued up mechanic, is of the opinion that the rail sensor is the culprit, but I'd welcome and other suggestions. I'm not going to deal with this right away, as there are some more pressing jobs to to - tracking and new front tyres for a start, but at some stage I do want to get it sorted.

Over to you chaps…!

[Stickyfinger]

The pressure regulator is one of the "common" faults on the car, not sure if the sensor is ?,
?? When was the fuel filter last changed ?...they do not last much longer that a service interval in many cases.

[Stewart(oily)]

I could provoke similar behaviour in my Xantia, I replaced the turbo electrovalve and its gone
The failed one was sort of working, but booting it lit the light, performance and flexibility are also much improved.

[DickieG]

The fuel pressure sensor is located on the fuel rail which runs across the engine below the injectors, often when you have a pressure fault the engine will tend to run on for a second when you turn it off. Anyway to sort it out remove the electric plug on the señor and ensure the contacts are clean using some electric contact cleaner spray. If that doesn't resolve it there might be some dirt on the pressure regulator pin which is located on the pump, remove and clean ensuring absolute cleanliness no dust/fluff etc.

[centurus2400]

I replaced the fuel filter recently, without any effect. The old one looked clean enough, with no unpleasant surprises in the housing!
Performance is first rate, and neither does the engine run on at all, though I will check this very carefully.

Looks as if the first thing to do is to clean those connections!

Thanks for the suggestions

If the rail regulator did need to be changed, what sort of costs are we looking at?

[Stickyfinger]

Depends on the car, post the last 8 of the vin and it can be priced.

BEFORE buying anything.....does the live data from the Lexia not tell you what the pressures are ?

[RichardW]

You also need to look at what the pressure reg is doing. e.g. If the expected value is 75% or something, but it's having to ask for 100%, then it's probably the reg at fault.

These are (possibly) the parts. The pressure sensor is not listed separately to the rail oddly, but that's not to say you couldn't get it from somewhere else if you can get a part no off it.

Part Number Description Quantity Price excl. VAT Price incl. VAT Total incl. VAT Selection
0000193341 REGULATOR 89.52 GBP 107.42 GBP 107.42 GBP

00001570N5 INJECTORS SUPPLY RAIL 175.60 GBP 210.72 GBP 210.72 GBP

[centurus2400]

So far I've been looking more at the logged faults rather than the live data.
Certainly if the simple no cost cleaning option doesn't produce any improvement than I need to delve deeper into what's going on before spending any money.
As I said currently the fault is only intermittent, and at wide open throttle, so under ordinary driving conditions it's not causing me any problems.
It's good to have a better understanding of what I'm up against though.

As an aside, the local main dealers wanted to charge me £50 + VAT just to read the codes...

[Stickyfinger]

As an aside, the local main dealers wanted to charge me £50 + VAT just to read the codes...

eg, 3/4 of a Lexia on EBay....LOL