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Hi guys I'm new here. I've just bought a 406 2.2hdi and it's coming up with anti pollution system defective and the management light comes on and stays on when driven I think above 2500 rpm it looses boost which I assume is going into limp mode however when you stop turn and start driving again it drives ok but still goes into limp mode. When driving you can hear the turbo spool up it's not loud but you can here clearly and also when you back of the revs. I've had it plugged and there's a turbo boost sensor fault, I've had a look for split pipes but can't see anything I really am stuck now and would be grateful for anyone's help !
Thanks

Hi & welcome

engine anti pollution system defective is a generic error message that could mean literally anything (but usually something electrical), so the only way forward is to get the code read -- which you have.

I think the next step is to replace the offending sensor (this has always worked for me, although mine is always the throttle position sensor).

Good luck & let us know how you get on

Hi & welcome to the site.

As rwb says, Antipollution Fault is just pug-speak for any engine ecu related problem, but as you have a pointer to the boost pressure, the most common failing is over-boosting as a result of vacuum system problems, (the ecu detects excess pressure, then limits boost & fuelling to protect the engine, aka limp mode). Your 2.2 HDi has a variable geometry turbo and counter-intuitively it needs a working vacuum actuator to reduce the boost pressure. You probably have a very minor vacuum leak.

These problems can be difficult to diagnose, but generally are simple and fairly cheap to cure, once you know what the cause is. Also, it's very unlikely to let you down completely.

The definitive guide on this subject is on the coupe forum - worth joining just to read this article if you have a DW12. http://www.406coupeclub.org/PHPBB3/view ... 82&t=35570

Good luck, let us know how you get on, or if you any questions.

Hi guys thanks for the reply. I've borrowed a snap on Ethos and read the code and it's code P0235 Turbo Pressure signal. I cleared the code and it doesn't come back on until you go past 3000 rpm and as I said before you can hear the turbo spool up which correct me if I'm wrong but you shouldn't hear it ! Anymore ideas would be great cause I'm stumped :-(
Thanks Simon

I've always been able to hear it on mine - it's particularly noticeable when cold as the air is diverted through the water-heated exchanger to speed warm-up. (Sometimes caught myself looking round trying to spot the ambulance or whatever causing the noise).

What does it mean when it's "defapped" ?

It's had the diesel particle filter, ('FAP' - Filtre Aux Particles in Pugspeak), removed and the engine ecu reprogrammed to work without it, (plus an extra 40-odd horses).

Looky here: viewtopic.php?f=10&t=12487

ok I am repeating what I was told as best as I recall it and it worked for me as I had pretty much the same thing.

There is an electrovalve under the airbox which fails and controls the diaphragm (its actually a rod I think its an actuator rod but the diaphragm is what Peugeot call it) one or the other or both may be goosed.

You can check the rod which controls the butterfly valves by moving the throttle cable and seeing if it moves freely. as you look at the engine cover the rod is to the right

I managed to get the electrovalve replaced and it is running better but the diaphragm wouldnt come out no matter what. It looks like it was held by 3 t20 torx screws set in a plate that had 3-5 bolts so I tried failed and figured thats one for the mechanic LOL Luckily it appears to have been the valve

I replaced the actuator on mine a few years back - access is much easier if you dismount the throttle position sensor and its mounting bracket. It's still awkward, but do-able.

Hi guys thanks but what does this actuator do? I've been out today and taken the intake pipe of turbo and thats fine. I did notice that to left side of air box there is a rid that goes to some sort of valve while reving car that rod is not moving however you move it freely with you hand. I really don't have a clue what to do.

That's your swirl flap actuator, which is meant to move upwards when you rev the engine. Sometimes the diaphragm in the base splits, or it could be a vacuum leak or electrovalve problem. Refer to the coupe club link I posted previously.