DPF help

NCC1701

My Qashqai broke its 4th air intake pipe last week (a common fault on these cars) and while I was driving in limp mode to get the replacement part, the engine management light came on. This never happened on the three previous occasions the air intake pipe cracked. I have a diagnostic tool and so I plugged it in and found that the fault showing was "ash in the DPF". I replaced the air intake pipe and while I now had more power, the car was still lagging and poor accelerating. I took the car for an hour's spin on the motorway keeping the revs at 2,500-3,000 to see if that would burn up the blockage but no joy as the fault light was still on and the diagnostic reader still showed ash in the DPF. I then put a can of JLM DPF cleaner into the tank and drove it again on the motorway for an hour to see if that would work but again, no joy. So now I think I'll have to remove the DPF and clean it out manually. Has anyone done this on a Qashqai before? I've seen a few youtube vids and it doesn't look too difficult.

The car, which is a 2011 model has 296,000 kms on it but its been serviced as per the manufacturer's guidance and I don't do stop start/short trips as my work commute is 80kms on motorway. However would the cracked air intake pipe have dislodged something to block the DPF or one of the lines leading to it? Any advice appreciated before I take the DPF off to clean it.

300k is about end of the life for DPF( if it is still original). Please, do not be D and delete the DPF. You can try to force regen but I do not think it helps anymore. The bottom section intake have a replaced part number (upgrade). Use that, not the first version. Check the waste gate adjustment, it may need adjustment. That can be the reason why you blow the intake.

zg3409

Has the dpf ever been replaced in the life of the car? If not it's probably full of ash and needs replacing. Beware cheap eBay dpfs as they often fail within a year. It may cost 700 euro plus for the part from a dealer plus a few hundred to fit in back street garage. Assuming dpf is full of ash often other things start to go such as the pressure sensor hoses right before and after dpf (these break off or open due to pressure and age). If there is any other issues with engine such as it being smokey, you probably won't know as smoke is trapped in dpf and it will block again. Avoid dpf clean services as they are not intended for high mileage cars with dpf full of ash and they cannot remove ash, only soot. Really ideally you get a good mechanic who knows the car type, knows the high mileage dpf issues and it could easily cost you 1000 euro. Then there is no guarantee that engine is not smokey and it will block again. Mechanic may run engine with dpf off to check.

NCC1701

https://www.boards.ie/discussion/comment/118261498#Comment_118261498

No the DPF was never replaced. I've since brought it to a local mechanic who was highly recommended. The guy connected his diagnostic tablet to it and then took it for a half hour test drive. He asked me a few questions about the car like the high mileage (just shy of 300,000kms) and I told him my job had me travelling all over the country on long drives. He said before I start spending money on the car (which is worth damn all at this stage but I can't afford to replace it), he said use some DPF cleaner in the diesel tank and take it for a long motorway run, which I'd already done but gave it another go. So I bought some more JLM DPF cleaner, poured it in the tank and off I went on the M7 to Portlaoise and back keeping the revs at 2,500 for the 2 hour trip. The result? The car was pulling better this time when I got near home but still not 100%. Next I put some dipethane in the tank and drove the 80kms to work and back. Car was running fine both ways and the engine management light stayed off. It's been running fine the past 2 weeks and so I think the cleaners finally did their job and have gotten me another while out of the car yet. I know its on its last legs but if it can last me another 6-12 months, I might be able to get a good 2nd hand car to replace it (or a cheap new one like a Dascia or a small supermini like a Swift) as I don't need a 7 seater anymore what with my kids growing up and doing their own thing.

Kencollins

I had the same issue with 2 Qashqais that I look after. The owner reported down in power, the turbo hose had come apart at the usual seam. The DPF code was stored in the ECU on both occasions.

My theory is that the hose may have partially split long before it was noticed. This will cause the engine to run very rich as all the air escaping has been accounted for by the MAF sensor. This will cause incomplete combustion, and then choke the DPF.

In both cases I was able to run a forced regen with the scan tool and rectify the issue. It took 2 attempts on one of the cars but it worked in the end. Both have mileage nearing 200K.

Maybe ask the garage to do a forced regen and a DPF re-calibration after. You never know!