C5 X7 fault codes - can anyone advise plz?

[steveclv]

So I plugged my new-to-me C5 X7 (2009 138 HDI FAP) into diagbox for the first time and found a few fault codes. A few were related to high fuel pressure at 3850 rpm in 4th (auto) but I decided to clear everything as I had no idea when they occurred so decided to start with a clean slate. However, a couple of them were persistent and I wonder if anyone has any advice

BSI code F5FF Unexpected re-initialisation fault coming from the BSI - Local - Not characterised

Electronically Managed Suspension code U2005 Triggering (vehicle speed receipt anomaly - Disant - Permanent fault

Apart from those, everything else seems ok but I will see if the fuel pressure faults re-occur over the next week

Thanks for any pointers

[GiveMeABreak]

Ignore all those, U2005 when appearing on a Global Test without other issues is a ghost fault, triggered by the interrogation of the Suspension ECU when the vehicle is stationary.

The other F5FF one is no concern, it's a common BSI one that happens every now and again.

[steveclv]

Thanks
I'm just wondering whether the battery needs changing as I have read that when cranking, if the voltage drops too low then it can cause an unscheduled reset of the BSI. Battery seems to be about 6 years old based on the service receipts so maybe worth doing anyway.
The other faults on the fuel system - mainly P0088 High fuel pressure based on my research elsewehere, where people have spent thousands replacing sensors, fuel rails, injectors and fuel pumps, might be just down to a fuel filter - weird I know but something to do with fuel starvation at WOT (I was at 3850 rpm, D4 and WOT) which when the throttle is released causes a momentary high fuel pressure condition. The filter was last changed 2 years ago so I'lll give it a try this weekend.

[GiveMeABreak]

Pop your VIN up when you get a chance so I can relate this other new code you have to the correct Engine ECU. Please post your VIN in full without spaces - it will be automatically masked from public view after submitting your post & will only be visible to staff.

[steveclv]

Thanks - here you go
VF7**************[VIN obfuscated, can be read by forum staff]

[GiveMeABreak]

It's also important to note the context of this fault and whether it appears as a result of the engine stalling or if it has difficulty maintaining idling speed, such as hesitation or not, because the context can help fine tune the fault. In the case of the the engine cutting out after starting for example, it's likely to be the fuel temperature sensor that is the culprit - or it's electrical connection.

As for the specific fault code in isolation:

Fault Code:	P0088
Description of Fault:	High pressure fuel regulation: The measured rail pressure is too high in relation to the set point. Description of the diagnostics The ECU detects a difference of 180 bars to 250 bars for 3 to 6 seconds between the rail pressure set point and the measured rail pressure.
Conditions for Fault to clear:	Driving for 5 minutes with several full load accelerations for 10 seconds
Downgrade Modes whilst Fault is active:	Deactivation of processing of the accelerometry Deactivation of the accelerometry strategies Deactivation of the detection of loop difference on the fuel flow rate regulator Deactivation of the injector flow rate correction strategy
Symptoms:	Jerking/stalling Unwanted acceleration Noise Smoke from the exhaust Lack of power Starting problem
Suspect Areas:	Engine ECU (Software not up to date) Poor fuel or polluted fuel (petrol, deposit, etc.) Problem on the fuel low or high-speed circuit (hose, tank, diesel fuel filter, etc.) Fuel injectors Engine fuse box Electrical harness Connectors High pressure fuel pump Fuel high pressure sensor

[steveclv]

Thanks
Assuming that it occurred when I was overtaking, then it exhibited no hesitation or limp mode like activity - just the warning message and the engine check light that extinguished the next time I started the car. It idles perfectly and runs just fine at normal speeds and accelerations - I don't think I have used WOT since that particular error.

However, I don't know if that was the situation that generated that error as the fault codes are not date stamped - I've attached a print out of the exact code results (I had to zip it up as pdf isn't a valid file type for the forum apparently)

Many thanks

[GiveMeABreak]

Here are the others - I've left out the Cruise Control fault (P1671) as that's nothing specific and will be deactivated whenever there is a fault with the engine management system.

Fault Code:	P1166
Description of Fault:	High pressure fuel regulation: Measured rail pressure higher than the maximum pressure. Description of the diagnostics: Pressure of the fuel high pressure common injection rail measured higher than the maximum pressure of 1800 bars for 6 seconds.
Conditions for Fault to clear:	Driving for 5 min with several full load accelerations for 10 seconds
Downgrade Modes whilst Fault is active:	Deactivation of the speed limiter Deactivation speed limiter until the next time the ignition is switched on Deactivation of the cruise control Deactivation cruise control until the next time the ignition is switched on Request for Delayed Engine Stop The ECU limits the fuel flow
Symptoms:	Lack of power Engine hesitating, cutting out
Suspect Areas:	Electrical harness Connectors High pressure fuel pump Engine ECU High pressure fuel sensor

Fault Code:	P0112
Description of Fault:	Intake air temperature signal (Air flow meter): Short circuit to earth; Value too low. Description of the diagnostics The voltage of the inlet air temperature sensor signal is lower than 98 millivolts corresponding to a temperature of 130°C for more than 500 milliseconds.
Conditions for Fault to clear:	Ignition on
Downgrade Modes whilst Fault is active:	Deactivation of the coherence faults of the flowmeter Deactivation of the airflow faults above the minimum threshold Change to "easy move" torque invalid Switching on of the warning lamp and/or warning message: Warning lamp MIL
Symptoms:	Jerking/stalling Lack of power
Suspect Areas:	Air temperature sensor on the flowmeter Electrical harness Engine ECU

Fault Code:	P0215
Description of Fault:	Supply relay control: Short circuit to earth or short circuit to positive or open circuit. Main relay remains stuck during the phase in which the engine management ECU becomes dormant.
Conditions for Fault to clear:	Ignition on
Downgrade Modes whilst Fault is active:	-
Symptoms:	Starting problem
Suspect Areas:	Engine fuse box Electrical harness Connector

[steveclv]

You see that's the problem - if you read the 'symptoms' then it implies that the car is undriveable but as I said earlier, apart from the error messages, the car behaved perfectly. I am suspecting that it might have been a fault that was already there and the error message is unrelated - or maybe it's the battery as they all suggest 'electrical harness'. I think I need to pull the fusebox/BSI off at some point to replace the gearbox mount so that will give me a chance to clean everything.

[GiveMeABreak]

Yes, always clear faults first if this is a new (to you) car, then go for a drive and re-read the vehicle.

These may be original faults that weren't cleared down. Only deal with them if they are re-triggered.