P0271 fault (mystery?)

[Argos69]

Hello all,

I never know why all the "issues" I have with the C5 2.2 Exclusive Auto, all turn to mysteries - maybe its just me?

Been for a long trip today and on the return journey "ping" "Engine Fault - Repair Needed" - ohh Great!

We limped home with an engine warning light and also a shuddering engine that felt like one cylinder wasn't working.

A Diagbox session at home revealed "P0271 Injector 4 Control Fault - short circuit to earth - harness, injector, ECU"
I lifted the sound mat off the engine and disconnected all the injectors. All injectors gave me 175kOhms of resistance (give or take).
I'm guessing injector 4 is the belt end?

So, now I'm worried that this may be a bit beyond me. I reconnected all injectors and fired the engine - no misfire!
Engine light off on the dashboard!
Checked Diagbox, fault gone and resettable.
I've been for a short drive, all ok.....

Any opinions or other things to check? Should I start carrying a spare engine?

Thanks for your time. As ever, advice gratefully received.

[Hell Razor5543]

I had an issue with my C5 last year, when she started running really roughly. It turned out that the connector for injector two had not been properly plugged in (so it had not latched), and over time the connector 'crept', eventually moving far enough for it to become disconnected. Once it was plugged in properly the engine ran normally. I wonder if you experienced something similar?

[Argos69]

Thank you Hell Razor,
Been for a 100km drive today without any issues, can this be it?
I am far too cynical to believe it's sorted by disconnecting and reconnecting. All my injector wires were fully "clicked", so didn't appear loose. I suppose it''ll take a while before I trust it and until then, it's a few tools and a multimeter in the back.

[tomaskriv]

Hi all

Had same issue....twice. First time engine off/on trick worked. Cleared code. Second time after about month. No chance to clear code. Rough idle and no power. Left car for a week because everyone closed for Christmas and new year... After starting the engine idle is perfect. Check engine light disappeared after few minutes....
All injectors connected with "click"....Shoud injector be replaced? Wiring looks ok. Hate tje ghost problems...cant trust the car now for long distances.

[Muir]

Might be worth removing each injector plug and spraying it thoroughly with contact cleaner and at the same time check the connection points are undamaged/uncorroded on both injector & harness.
Sounds like a fairly simple intermittent electrical fault, so most likely either the connector or worst case damage to the harness from ECU-Injector.

[tomaskriv]

Thanks Muir! Will try to get to that this weekend if weather will be ok...

[tomaskriv]

Scanner says intermmitent error.

This is whay I get after scanning. Checked all wires. Look ok. Car had one owner whe really loved his vehicle so all clean inside the engine bay...

[Muir]

Hmm what scanner are you using?
If it's a generic one it won't likely give you much usable info to go on.
I'm afraid tracking down this sort of intermittent fault will be difficult without Lexia/VCX/similar scan tool that can decode the the PIDs and DTCs.
You can try listening to each injector with "stethoscope" method or do a leak-off test to isolate if it's a mechanical issue and which injector(s) are affected.

[tomaskriv]

Ive used Autel MaxiCom mk808
Few machanics said that it is probably wiring/connection and not injector.
Booked to local dealer. See what they say....
Meanwhile car drives like rocket.