C30 1.6D Power loss - glow plugs?

[Tannaton]

So mother has a 2008 1.6D C30 SE which has only 32,000 miles on it.

Yesterday went into "Restricted power mode" - would not rev above 3,000 rpm. Before I could get to it with VIDA she took it to a local Indie who has diagnosed faulty glowplugs?

Whilst I haven't got the technical data I am struggling to understand how a glowplug fault could put the car into a limp mode.

Just to be clear - the message was Restricted power rather then Engine Service Required.

Any comments anyone?

[Ignatz]

Just from my own experience, I'd say the glow plugs aren't the problem. Early this year I'd had my C30 1.6D DPF/CAT replaced. Diagnostics showed a number of codes around that issue, but also one for the glow plugs. After the DPF work was done, the glow plug code wouldn't clear so I had them replaced. Only one of the four was still actually working, and with 80k miles hadn't been replaced since new. The tech who replaced them explained that high pressure diesels hardly make any use of the glow plugs, which is why they can fail without showing symptoms. Equally they never prompted a service message, only showing up on diagnostics. So in summary, I think the actual problem may lie elsewhere.

[Dancake]

It's entirely possible that glow plugs are the problem. Unlike the commonrail diesels of yesteryear, modern diesel engines make greater use of their glow plugs. The glow plugs are used to aid DPF regeneration by increasing combustion chamber temperatures. The 1.6D PSA engine uses the glow plugs in this way, and if the glow plugs aren't working, the engine will find it difficult to properly regenerate the DPF. It may even prevent the regeneration process from starting in the first place. Too many failed regenerations will put the car into limp mode.

[Ignatz]

Originally Posted by Dancake

It's entirely possible that glow plugs are the problem. The 1.6D PSA engine uses the glow plugs in this way, and if the glow plugs aren't working, the engine will find it difficult to properly regenerate the DPF. It may even prevent the regeneration process from starting in the first place. Too many failed regenerations will put the car into limp mode.

I didn't know that, so it shows how narrow my experience is. I think that two or more of my glow plugs hadn't been woking for some time. Maybe this was coincidental with the DPF replacement coming round as the diagnostics indicated. The Eolys tank also flagged up, taking a litre of fluid. If the glow plugs play such a key role in ensuring the regen process occurs, it's crazy that it doesn't flag as an ESSR message when they fail. It's as if Volvo take the view that the best way to let you know the glow plugs are knackered is to let the DPF fill up.