Peugeot 807 loss of power - EGR valve stuck open, or something else?

[HU807]

HI everyone. So we had quite an unpleasant summer with our Peugeot 807 2.0 diesel (2009 model year) this summer, and am now trying to figure out whether it’s worth fixing.

The problem started in late July with the dreaded anti-pollution system fault warning, with accompanying loss of power (I think due to limp mode). But on the next drive, the warning miraculously disappeared, power was restored, and it drove as normal. Earliest garage appointment we could find was September, so we figured what the hell and continued to drive it for another week or so … until it ultimately died on the highway. It gradually started losing power, spewing black smoke, and then finally sputtered out a coughing, chugging mess.

It still restarted, but by then there was some white smoke mixed into the exhaust (not thick, but strong smelling), the idle was very rough and noisy, and it couldn’t move more than 5-10 km/h. Pretty much zero power/reaction when I pressed on the accelerator. Just smoke. But no overheating. Initial fault code reading was P1352, which seemed to point to glow plugs … but that doesn’t seem right at all.

This week, the Peugeot garage finally looked at it. They say it’s a broken EGR valve, stuck in the open position. They tested it using a bypass and said the engine seemed to run OK like that, but was still spewing some smoke. They’re not 100% on what’s causing the smoke, but they think it’s excess soot and carbon that built up while the EGR valve was failing. But of course they can’t guarantee it’s only that. They say it’s possible the failed valve may have caused other damage, but can’t tell until they fix the EGR (already 1,000 EUR).

My question: What are the chances that the broken EGR valve caused damage to the engine? My research on that isn’t coming up with much. And perhaps more importantly – would a broken EGR valve alone have caused these symptoms, or would it seem likely that there are other issues?

Thanks in advance for any wisdom you might be able to offer!

[GiveMeABreak]

It will be impossible for us to say one way or the other - that's why the garage also can't tell you until it has been replaced and tested. All the black smoke and other stuff is what has likely already gone through the engine via the EGR valve and back out through the exhaust.

However, the clue and your glimmer of hope, is that they have already told you that the car seems to be running OK whilst they had the EGR bypassed temporarily, so getting the EGR replaced may be it with luck.

Don't forget the other location is the air intake manifolds - these too will at some point start to clog with sludge, so it may be worth getting those cleaned up at the same time.

[wheeler]

If the EGR valve has been blanked off (for testing) I would expect i would probably need driven hard for a good few miles before the smoke would clear from the exhaust, do you know if this was done?
If the EGR valve has been sticking open for some tome this could also lead to rapid clogging of the DPF.