2021 MAN TGE - recurring P2459 despite new DPF pressure sensor

[ChrisG]

Hi all, looking for some advice on a recurring P2459 – DPF Regeneration Frequency on my 2021 MAN TGE 2.0 TDI DAUB, 6-speed manual, around 59k km. It’s a camper conversion and runs permanently at roughly 3.3 tonnes.

The fault has now appeared three times, with the codes cleared twice in between. The van drives completely normally with no limp mode, power loss or obvious smoke.

A technician replaced the DPF differential-pressure sensor because the old one had shown implausible/negative readings, but P2459 subsequently returned.

I’ve since bought genuine VCDS and done some logging. The replacement pressure sensor appears to behave consistently: approximately 0 mbar engine off, 20 mbar warm idle, 52 mbar at 2500 rpm stationary, and up to around 250–260 mbar under very heavy load. Pressure follows exhaust flow very closely.

When the latest P2459 was recorded the freeze frame showed 2530 rpm, 79.6% load, 461 m³/h exhaust flow, 220.6 mbar DPF pressure and almost exactly 30 g calculated/measured soot.

I’ve also logged requested vs actual boost and turbo actuator position, which both look very good. Rail pressure follows requested closely. Injector 4 is a slight idle-balance outlier, but nothing so far strongly suggests a failed injector.

On a recent ~1-hour drive the van went from roughly 198 km to 257 km since the previous regen without requesting another regen. Calculated soot only rose from about 13.1 to 14.3 g, while measured soot rose from about 15.5 to 19.1 g.

One possibly relevant detail: the problem first appeared after I changed the air, fuel and oil filters earlier this year. The oil meets VW 507.00. I don’t believe the air-filter adaptation was reset afterwards.

I’m currently waiting to catch a complete natural regeneration with VCDS so I can see the trigger point, pressure/temperature behaviour and post-regen soot values.

I’d be very interested in opinions on whether the ~20 mbar warm-idle DPF pressure looks excessive for this engine, whether the soot-model divergence is significant, and whether anyone has seen P2459 caused by injector issues, air-filter adaptation, residual DPF restriction or ECU software on the DAUB.

I have the full Auto-Scan and CSV logs if useful.

Any help is really appreciated.

Cheers

Chris

 

[Archie H]

I think you might be better requesting this from Ross-Tech who provide great support.

 

[ChrisG]

I did take a look at the Ross tech site and wasn’t sure how to contact them, I’ll look again. Thanks

 

[mmi]

20 mbar warm idle

Calculated soot only rose from about 13.1 to 14.3 g, while measured soot rose from about 15.5 to 19.1 g.

Not good signs

I have the full Auto-Scan and CSV logs if useful.

Please share.
Also a couple of VCDS blockmap files would be helpful.

1) ignition ON, engine OFF​

2) cold engine idling​

3) hot engine idling (after 20+ minute journey). Ideally stop/start turned off for the whole journey.​

How-to:;

​

• Tick the boxes as above and click Go
• VCDS flashes screen for approx. two minutes. When finished click Done, Go Back

The result files (.csv) are saved into directory C:\Ross-Tech\VCDS\Logs

 

[Archie H]

I did take a look at the Ross tech site and wasn’t sure how to contact them, I’ll look again. Thanks

You will need to do FULL SCAN and upload the results on Ross Tech. then one of the gurus will review the file and make recommendations. You do need to join the forum free. Read all the instructions as well. Although you seem to know your way around to have determined the info you have uploaded on this forum. HtH.

 

[Raul a/3]

From what I know, the EGR flow is to look at. It is directly linked to DPF pressure sensor and DPF flow.
A sooted EGR cooler can trow the ecu in thinking you have a DPF problem, a computer logic.
I had insufficient regeneration, with DPF relatively healthy and differential pressure reading within expected values.
That prompted me to EGR flow as all are dependable on each other and linked.
So I took the egr and cooler apart. The cooler was almost blocked, and before that the vcds did point to low egr flow. Changed with mew cooler, gaskets, and kept the old EGR. The new egr had a fault, and couldn't do a successful adaptation. So cleaned the old and bolted to the cooler. So far no light/fault for quite some time.
I would check with vcds for egr flow pressure anything related to flow. Ask AI and will give you clear instructions for vcds, what values to read and what to expect. AI did helped me.