406oc.co.uk

Hi,
Im no novice mechanic, but Im not at all familiar with the Peugeot set up.

I've had it quite a few years, and there has always been an intermittent fault, mainly when its cold the STOP light will flash and beep and then it stops as the engine warms up. The PO said it had 'always done it and I put this down to an intermittent sensor or connection.
I dont think this is related to the 'new' issues that I have, but thought I would mention it in case...

A few weeks ago it seemed a bit down on power. Not a lot, not in limp mode, but just not pulling as well as it did.
I then noticed that the brakes felt a little weird, inconsistent. They always worked, but sometimes it felt like they required a bit more pedal pressure or were coming in with a slight delay. I was pondering if it was a servo issue and checked all the pipes/hoses but couldnt see anything wrong.

Im not familiar with these engines and how they work, but I did notice that there are vacuum feeds to two smallish solenoid valves nounted on the bulkhead. A bit of detective work leads me to believe that one of them controls the turbo waste gate.
So I was wondering if either one of the solenoids was sticking or non-operative and bleeding the vacuum so that it affected the brakes and performance (waste gate stuck open?).

I took both solenoids off, cleaned and inspected them and swappped them over to see if symptoms changed. The brakes and performance seemed a bit better but still not right.

Next I found my OBD and read the codes;
P0115 Engine Coolant Temperature Circuit Malfunction (faulty temp sensor?)
P0380 Glow Plug/Heater Circuit "A" Malfunction (never had a problem cold starting)
P0243 Turbocharger Wastegate Solenoid A Malfunction (aha! could this be a clue to the issues?)

Ive got a couple of solenoids coming down from Ebay, so plan to test them on the bench and then fit to the vehicle to see if the issues change or go away.

My main question and reason Im posting here is to ask if there are any other known issues or if anyone has any thoughts on what else I can check or test?

How would I check if the vacuum pump is working OK?

Thanks
Mike

This sounds like a leak in one of the vacuum tubes. Check all of them visually for damage.

Here you can find pictures of the vacuum system: https://406oc.co.uk/viewtopic.php?t=21522 . It depends on the build date if you have a third solenoid (for the "air doser").

Here is another document describing the vacuum system: https://www.qclt.com/html/%E6%A0%87%E8% ... hg2uk3.htm . It is for a 2.2 HDI, yours is a 2.0 (is it?). So in your case you don't have (7) Proportional solenoid valve of the pef (particulate emission filter) mixer control and (8) Swirl control solenoid valve . Possible you also do not have (6) Egr metering control proportional solenoid valve (= air doser) .

If you don't find any apparent broken vacuum tubes you can block off the tubes towards the three (or two) solenoids on the bulkhead. Keep the tubing towards the brake servo. If the braking is fine, plug in back one by one the tubes.

Thanks very much for the reply.
I have already checked the hoses/pipes as well as I can. No signs of damage or leaking that I can detect.
There is no third solenoid.

Thats good advise re blocking them off. I wasnt willing to do that without understand what function they performed.

I will check the diagrams you linked and hopefully that will make matters clearer to me.
I think my next step will be to test the replacement solenoids I received and swap them out.
Then if that doesnt fix it I will try blocking the vacuum feeds near the solenoids and see if it changes.

How would a poor vacuum feed to the waste gate affect running? i.e. would the waste gate be stuck open or closed without vacuum?


P.S. Yes, its a 2.0 Hdi

How would a poor vacuum feed to the waste gate affect running? i.e. would the waste gate be stuck open or closed without vacuum?

There are various opinions about this. As far as I can see from this document, page 25, diagram "E" and page 26:

montage (E): au repos la soupape régulatrice est ouverte" (at rest the regulating valve is open)

where "open" means: the exhaust air is diverted, away from the turbo.

Also on page 27 of that same document:

La pression de suralimentation est régulée par l'électrovanne (4) pilotée par le calculateur (1)
Attention : La soupape régulatrice est ouverte lorsqu'elle n'est pas commandée pneumatiquement (dépression)
La montée en pression dans la tubulure d'admission est obtenue par la fermeture de la soupape régulatrice.
Dès que le calculateur d'injection interdit la commande de l'électrovanne (4) pour limiter la pression de suralimentation :
la pompe à vide n'est plus en communication avec la capsule de commande (9), la soupape régulatrice de pression de suralimentation s'ouvre, la vitesse de la turbine d'échappement diminue, la pression d'air de suralimentation diminue

Or via Google translate:

Boost pressure is regulated by the solenoid valve (4) controlled by the computer (1).
Caution: The regulator valve is open when it is not pneumatically controlled (vacuum).
The pressure increase in the intake manifold is achieved by closing the regulator valve.
As soon as the injection computer inhibits control of the solenoid valve (4) to limit boost pressure:
the vacuum pump is no longer in communication with the control capsule (9), the boost pressure regulator valve opens, the exhaust turbine speed decreases, and the charge air pressure decreases.

So no boost when no vacuum.

Thanks!

So faulty solenoid could explain all the symptoms Im getting.
Good to know!

Hi,

Can anyone confirm how these work?

They appear not to be a 'normal' solenoid valve (12v on terminals to operate valve), but are a "pulse driven variable actuator" so can they be tested off the vehicle?

Thanks

I swapped both of them out for some used ones from Ebay and its driving and stopping a lot better.

I would still like to understand what they actually are and how they work, but thanks for all the info.

mikeau wrote: ↑Tue May 20, 2025 3:39 pm I would still like to understand what they actually are and how they work, but thanks for all the info.

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