C5 2.2Hdi mk1 anti pollution nightmare

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vinypeps
Posts: 29
Joined: 10 Jul 2012, 19:50

C5 2.2Hdi mk1 anti pollution nightmare

Post by vinypeps »

New topic old problems.
I’ve got an early MK1 C5 2.2 hdi with the perennial anti pollution/esp-esr fault, and I’ve got to the point where I’m totally at a loss now, I remove all the warning faults via Lexia then take the car for a spin, the second that the turbo starts to boost ( usually a couple of hundred yards ) it backs off and drops in to limp mode.
I’ve read loads of the very helpful posts on here that go back years, I’ve worked through a few of the different areas recommend by the posts I’ve read on fcf, I’ve replaced the swirl valve, maf sensor and turbo actuator solenoid so far, I’ve checked the vacuum lines with a gauge and a vacuum pump, no leaks, turbo actuator works with the vacuum pump connected at the actuator and when the pump is connected to the outlet of the actuator solenoid.
The Lexia readout Comes up with,
P0235 permanent fault, turbo pressure signal coherence with atmosphere.
P0243 Turbo pressure electrovalve short circuited to earth or open circuit.
I’m guessing at this stage that I have an electrical or Ecu fault somewhere, I’m ok with the mechanical side of things but not so hot on how to check for wiring or ecu faults unfortunately, I’ve done a visual check on the wiring to all the various solenoids with no obvious broken wires, but wouldn’t know where to start on checking for internal wire breaks or loss of signal from or to an ecu,

HELP...

wheeler
Posts: 4383
Joined: 21 Sep 2002, 19:07
x 164

Re: C5 2.2Hdi mk1 anti pollution nightmare

Post by wheeler »

You haven’t said if you checked all the turbo pipework & intercooler for leaks?
I would have thought with a wiring fault it would re appear as soon as the ignition was switched on, the fact it doesn’t re appear till the turbo starts to boost suggest its the pressure sensor is not seeing what its expecting to see.
Have you had a look at live data from the boost pressure sensor & atmospheric pressure sensor?

vinypeps
Posts: 29
Joined: 10 Jul 2012, 19:50

Re: C5 2.2Hdi mk1 anti pollution nightmare

Post by vinypeps »

Hi Wheeler, thanks for the reply.
The faults do reappear on the Lexia when the ignition is switched back on after doing the fault removal, if you don’t turn the ignition off and then clear the permanent remaining faults again it resets ok, the service light and anti pollution warning disappear when you start the car, but drive it a couple of hundred yards and it goes to limp mode again.
As for the intercooler I think it could be leaking, there is oil leaking at the bottom of the inter cooler, how would I check the operation of the intercooler and pipework?

wheeler
Posts: 4383
Joined: 21 Sep 2002, 19:07
x 164

Re: C5 2.2Hdi mk1 anti pollution nightmare

Post by wheeler »

The pipework would be a visual inspection for splits, get someone to rev it up while you go round the pipework, you should feel the rubber pipes puffing up when the engine is revved, listen for air escaping.
Temporary bypassing the intercooler by joining the inlet & outlet pipes together is a good way to check it, depending on the shape & locaton of the cooler this can be easier said than done sometimes.
The other way is to make a up a soapy water solution & spray it on whilst someone revs it to check for escaping air.