1.5 DCi running problems + TF warning

[ohnomegane]

Hello - I've searched through this thread, but the problems all seem to be for petrol engined cars there.
My other half has a 1.5 DCi, 2004 04, which has been running rough, losing popwer and is now apparently producing some black soot/smoke out of the exhaust. The plan was to get it hooked up to a machine at the weekend, but this morning the Toxic Fume warning light has come on (and stayed on) along with the service light.

edit: she rang the dealer - Reanault in Derby - who were very non-commital about whether the car was driveable and what the problem might be. They of course want to get the car up on a ramp asap so they can get their bill going, but I'd prefer to take it elsewhere other than Renault. Is it driveable? Should she get a tow home from the AA?

Is anybody aware of a problem which might display these symptoms?

[AlexB]

The context of failure is important for diagnosis, so you may want to tell us more, in fact everything about this car. Perform a basic check as well -- visual, sound, smells, oil level/quality, coolant, check glow plugs for traces of oil.

Regarding your question, you may be adding catalytic converter or the turbo to the bill by using the car in this condition. Somebody earlier mentioned a possibility of injector fault which develops into a piston failure -- this is expensive.

[ohnomegane]

Good point
Right 2004 04 Megance DCi 80 Dyn'. 68k miles, serviced at specified intervals by Renault techs at Renault dealers (either franchise or main dealer depending on price). 2 weeks ago was told that there is something "wrong" with the car - it's not pulling strongly like it should, wasn't accelerating above 50mph, but apart from that seemed ok. Fuel economy OK around 55mpg, car drives a 100 mile round trip commute each day on M1.
I drove it - not my regular car, so couldn't compare what it was usually like and it seemed alright. Pulled ok through all gears - 50 - 80 mph in top was good, overtaking fine, no lumpiness or rough running evident. Ran it for the week and on one evening commute from work, noted a big puff of soot from a normally otherwise clean exhaust. Was pointed out yesterday that car was still running rough, more smoke than normal and this morning the TFF warning light comes on solid with service light. Apart from that, the car sounds alright, looks alright, drives ok, has plenty of oil/coolant. I'm not going to take the glow plugs out as I have neither the tools nor the expertise.

AA have been out and have reported following fault codes:

P0409 Exhaust Gas Recirculation sensor A circuit

P0487 Exhaust Gas Recirculation throttle position control circuit

P0670 Glow plug control module control circuit/open.

The AA tech has said he sees a lot of this and that it's not necessarily a fault with the sensors or the ECU. He's reset the ECU and cleared the fault codes and has said it's not necessarily going to cause damage by driving it, but if it happens again, it should be looked at. So it sounds like if it does happen again, it's possibly a sensor fault.
Anybody in agreement?

[AlexB]

Glow plugs only work on cold engine.

The EGR valve if stuck open may cause soot and poor running. It is supposed to be fully closed at idle and full throttle. If not, then it will affect these modes.