Citroen C4GP Turbo boost electro valve

[jonboy7300]

This is a long-standing problem that we’ve just got used to. But it’s annoying. Given that this forum has been soo helpful, I thought I’d give this some air.

My other half’s Citroen C4 GP. Basically, it ran fine. Then one day it lost power. There was no event, it just lost all enthusiasm. I have three 1.6HDI’s in our fleet, so I’m used to the usual turbo games. I set about checking through all the mechanical bits and systematically swapped out parts to make sure that we had no boost leaks or anything simple. The turbo is good. Mechanically, all is well.

I’ve plugged it in to Lexia to find “Turbo pressure electro valve control” error.

I’ve replaced the valve. I’ve checked all the vacuum system. I’ve been around the wiring loom where it loops across the gearbox to the fuse box and under the car where the value lives. I can’t find any damaged wiring, and no corroded plugs, etc. Basically, I’ve done all the Internet forum basics to no avail. The cars also been in the local garage, they had no success either (they just decided it wasn’t worth the effort).

The turbo is running, just not boosting (as you’d expect with a control issue).

So, I enlisted the help of a good chap who does remaps and stuff. We went around everything again and started to look at bits like fuse boxes and ECU’s. The ECU has been changed, and I have now permanently replaced the fuse box (that was done to cure a windscreen wiper issue (thank you soooo much to Marc @GiveMeABreak for that!)).

Eventually we discovered, after extracting some data (file can be viewed at the following link https://docs.google.com/spreadsheets/d/ ... ue&sd=true), that the throttle position sensor was giving weirdo readings. If you sit in the car and slowly move the throttle up and down, the readings are inconsistent and don’t directly correlate to the position of the pedal. We changed out the throttle pedal assembly, no different. At this point we gave up and I accepted that the car would just be gutless.

Does anyone have any thoughts as to wtf is going on and where I might look for answers? I’ve literally run out of ideas and people to ask.

[GiveMeABreak]

If you can provide the actual fault codes being returned and the VIN for the vehicle concerned I'll have a look. Obviously Lexia / Diagbox preferred as these will be able to read the constructor faults.

[jonboy7300]

Sure. Diagbox says P0243.

The Vin is: VF7**************[VIN obfuscated, can be read by forum staff].

Thank you!

[GiveMeABreak]

As you can see until this is resolved the engine ECU will put some operations into a downgraded mode to protect the system.

Fault Code:	P0243
Description of Fault:	Turbo pressure regulation electrovalve control: Open circuit. Open circuit or value too high for 1s.
Conditions for Fault to clear:	Ignition on
Downgrade Modes whilst Fault is active:	Cutting of the EGR butterfly (turbo air cooler), EGR valve and bypass butterfly (inlet air heater) in all operating modes. Cutting of the "exhaust heat recovery" function. The ECU deactivates the programming cycle of the turbo valve. Cut in the programming of the stops of the turbo actuator.
Symptoms:	Lack of power
Suspect Areas:	Electrical harness Connector Fuse F20 on fuse box PSF1 Turbocharger control solenoid valve

[jonboy7300]

Yeah okay, that makes sense.

None the wiser as to where to look though. I’ve been through the suspect areas; solenoid replaced, fuse F20 is good, no apparent connector issues, nothing I can find that even remotely looks like harness damage.

I have to say, I’ve just plugged Lexia in now and the fault is not there. The car still performs exactly the same, but there’s no warning light and nothing showing up as a fault?

It’s a silly game!

[GiveMeABreak]

The fault may trigger again once the conditions are right - what about the valve? What brand is it and where did you get it from? ECP by any chance???

[jonboy7300]

Afraid I can’t remember what brand it was. It would have been cheap though. Had an idea that it was an Amazon special, but I can’t find it in my purchased items, so I guess not.

Is there a chance that the new valve is junk?

[GiveMeABreak]

Yep. Always try and buy a branded part is my advice especially when it comes to sensors and valves etc. Not saying this is the cause of course, but it does help if you know you have a decent part.

[jonboy7300]

That’s fair.

I did try out a valve from one of the other working cars though (now my brains on). So theoretically the valve isn’t the problem? Although point taken.

[jonboy7300]

Finally had a bit time to go play about with the car today. Firstly, I’m please to say that it’s up and running again and driving quite nicely (with working windscreen wipers, door locks, everything!).

Ran diagnostics on Diagbox, I now have a few more faults coming up. And the electro-valve error is back (although I have to say the car feel really quite spicy compared to how it’s been).

New errors are:
F000 - Fault engine wiring housing: eCU mute on the CAN
F8EB - Fault absence of +Permanent on the display
7159 - Oil level information fault
FB8B - Fault: Stop and Start switch jammed

WTF are all of these, and why are they suddenly appearing now? Thought it might have been something to do with the new engine bay fuse box, so I cleared them all, ran the car for a bit, and re-scanned. All back again.

It is definitely the gift that keeps on giving!

[CAP777]

Hi... I know this is an old thread but how did you sort the issue out? I am having the same issue with no success.