[Processing61]

Hi guys,

I’ve had the car for 3/4 years (on 211k miles) and the DPF has been an issue with the previous owner and me. Whenever the ignition is on (engine doesn’t have to be on) for about 10 mins I’ll get the dpf warning light on the dash.it doesn’t and has never gone into limp mode as yet, the symptom is only the DPF light on the dash.

Sometimes in the past id use a bottle of wynns dpf cleaner and pour it directly into the dpf lambda/oxygen sensor hole and after a week or two of driving the dpf light would clear and not come back for maybe a couple of months but that isn’t working anymore. Not to say this method is good, it was just what someone recommended to me and worked for a period of time.

I’ve got the launch creader elite BMW tool (I do have access to inpa and ista too) so I erased all the codes, drove the car for a day or two and checked the codes again and in the HISTORY, I’ve got 452A (DDE: Info - Particulate-Filter System) and 4252 (DDE: Glow Plug, Cylinder 5, Activation). In the current log/errors I get 480A (DDE: Particulate-Filter System), 481A (DDE: Particulate-Filter System) and 4D00 (DDE: Exhaust Backpressure Sensor). I was getting an error to say the DPF needed replacing as it had past 250km miles, so I have reset that value, just to see if that helped but it didn’t. It does actually say 4143872h before its last successful regeneration so that’s not good if true.

Live back pressure data; after a shortish drive I’m getting 70mbar idle and after running for maybe 10secs at 3k I’m getting 430ish mbar. And was idling steady at 89.5 degrees so seems thermostats are ok and are open as I believe they open at 89.

I’m thinking I’ll replace the glow plug module and if it needs it, glow plug on cylinder 5 too as I guess that could stop it working optimally. I also want to do a smoke/leak test for boost and vacuum leaks as I understand that could cause the dpf to not run well. From what I’ve looked at online a good DPF would read under 10mbar at idle and less than 60ish at about 3k revs.

As I say I’ll change the glow plug module, check for leaks and once that’s all good, use a cleaner. I was thinking the wurth DPF cleaner (https://www.dortechdirect.co.uk/cata...hR7399fqFbrEMY) spraying it into the hose of the dpf where the pressure sensor connects. Then, if it helps bring the mbar back pressure values down, see if I can force regen it after that.

So I think my questions are, am I troubleshooting in the correct way? Is there any common issues that cause the dpf to not work efficiently and keep getting blocked up? Finally, what is the best way to manually clean it first to try and get the pressures down before trying a force regen?

Appreciate any advice and apologise for the long message.

[Andy198712]

I’m pretty sure it won’t regen if there is a fault with the glow plugs or egr, or if coolant temp is too low.

I’ve got the N57 325d but I’ve replaced my glowplug controller twice now and never the plugs them selves.

Deffo sort that first, check your coolant temp too with your code reader or hidden menu, and have more then 1/4 tank of fuel in the car.

[Andy198712]

I wonder if the back pressure sensor code is an issue too or just saying it’s too high pressure?

[Tambohamilton]

I've run mine (M57N2 30d) for years with glow plug errors. For a time it had codes for 5/6 plugs! But I've never (touch wood) had any dpf issues. YMMV I suppose.

Have you monitored coolant temps while driving? And like Andy says, make sure there's plenty fuel in the tank.

I believe ista d has a test sequence for the dpf back pressure, where it monitors pressure at idle, 2k....and rev limiter. The first 2 it does automatically, the last one is manual. I've never done the last bit, because the neighbours would be out with pitchforks!

The only dpf cleaning that has a hope of working would involve taking it off the car...even then I'm not sure what chemicals would be best. I've wondered about sending mine off to have it cleaned by a specialist.

[Processing61]

Originally Posted by Andy198712

I’m pretty sure it won’t regen if there is a fault with the glow plugs or egr, or if coolant temp is too low.

I’ve got the N57 325d but I’ve replaced my glowplug controller twice now and never the plugs them selves.

Deffo sort that first, check your coolant temp too with your code reader or hidden menu, and have more then 1/4 tank of fuel in the car.

I wonder if the back pressure sensor code is an issue too or just saying it’s too high pressure?

Yeah I'm going to replace the glow plug controller first and if there still is an issue on cylinder 5 after, I'll change the glow plug too.

No errors for the EGR but I haven't physically checked it to see if its blocked.
I believe coolant temp is ok as I was idling at 89 degrees when warm which I believe is when the thermostats open.

I'm not sure exactly what it means regarding the back pressure sensor. I was thinking it meant the pressure was too high but maybe it could be a bad sensor. But it wasn't doing anything weird when looking at the pressure changes when idling and increasing revs etc, the sensor seems ok

[Processing61]

Originally Posted by Tambohamilton

I've run mine (M57N2 30d) for years with glow plug errors. For a time it had codes for 5/6 plugs! But I've never (touch wood) had any dpf issues. YMMV I suppose.

Have you monitored coolant temps while driving? And like Andy says, make sure there's plenty fuel in the tank.

I believe ista d has a test sequence for the dpf back pressure, where it monitors pressure at idle, 2k....and rev limiter. The first 2 it does automatically, the last one is manual. I've never done the last bit, because the neighbours would be out with pitchforks!

The only dpf cleaning that has a hope of working would involve taking it off the car...even then I'm not sure what chemicals would be best. I've wondered about sending mine off to have it cleaned by a specialist.

In the past I have but not for a long time. I only checked to make sure it was up to 89 degrees when idling as that's when the stats open. Maybe I could look while driving too.

Thats good to know about the test sequence.

I hear you. From what I've read removing the DPF is a PITA and not a job I want to entertain if I can help it. I did have a 330D saloon previously which I had the DPF "solution", EGR blanked and mapped. But getting round the MOT and the smell that it gives off (not thinking about the environment and health) wasn't ideal and i'd prefer not to do that again if possible. Equally don't want to buy a new DPF as its so expensive. Trying to make the DPF last as long as possible lol

[Tambohamilton]

If it's just sat idling, of course it'll get to 89deg. No air through the rad to cool it down. When you're moving though, a failed (open) stat will stop the engine from reaching temp.

Yeah, even just looking at the dpf in situ makes me dread the job...hate to think how much else would need to be removed.

Watched a few videos last night showing cleaning the dpf in situ, seemingly with good results. I still trust nobody though

[Processing61]

Originally Posted by Tambohamilton

If it's just sat idling, of course it'll get to 89deg. No air through the rad to cool it down. When you're moving though, a failed (open) stat will stop the engine from reaching temp.

Yeah, even just looking at the dpf in situ makes me dread the job...hate to think how much else would need to be removed.

Watched a few videos last night showing cleaning the dpf in situ, seemingly with good results. I still trust nobody though

Oh yeah of course. My bad 🫠. I’ll check that on my next drive. So once warm and at operating temp I’d want to see it 89-95ish while driving.

If I had a lift or access to a lift, maybe I’d try it. But then again maybe not lol.

When it gets to that point I do actually have a gun that I can use with my air compressor to put liquid in and shoot it out compressed. The guns rated to 100psi so I could shoot it out at say 70-80 psi through the dpf pressure sensor hose into the dpf. That seems to be what the mobile dpf cleaners do on vids I’ve seen. They use a higher pressure though. That’s going to be more effective than what I’ve done before. I’ll have a look to see what liquids/chemicals are recommended

[Tambohamilton]

I think for regen you need over 75degC. But 90deg is normal.

Let us know how it goes with the chemicals...