Hi guys,
I have the dubious luck of frequenting various mechanics in the last month for DPF issues. The filter gets clogged, we force regeneration and soon the same happens. I read the very useful topics on DPF issues and summarized below the most frequent culprits.
I try to deduce which of them is mine. The last thing we did is change a temperature sensor, before that we changed differential pressure sensor and I can keep changing as the mechanics are not sure where the reason is.
The last thing they told me is the EGR valve has issues, 1000 pounds and all will be fine. Of course they said this after 400 pounds for temperature sensor
I got almost instantly the DPF full red light without the yellow one and I got if after an hour on the highway - sounds like turbo drain mode.
After the last forced regen I got restricted performance switching off and on. And I have EGR error bank 1 at 100% which according to mechanic means EGR is always open and that clogs the DPF.

What do you think?

Here is my list of the usual suspects:
DPF associated issues
- turbo oil drain mod
- a leaky air duct or maf sensor (leak of the inlet air), if the maf sensor does not work well or an air duct is cracked behind the maf sensor, not enough air may enter, but more fuel - which makes more carbon deposits and clogs the dpf; the air line from the filter to the turbo (induction hose); turbo hose leak (bringing air from turbo to engine)
- over-fuelling due to leaking fuel injectors (can trigger check engine light) - also injects more fuel and can clog the DPF
- DPFs require a special low-ash oil C1 instead of A5
- leaky turbo oil seal
- faulty EGR valve - pumping excess crankcase vapor into the exhaust
- exhaust gas temperature sensor faulty - would not let regeneration start
- faulty glow-plugs - also DPF-deadly - because they cause the engine to run too rich on start-up or a fault of glow plugs prevents the regeneration to start
- differential pressure sensor error
- if the thermostat is faulty, the computer would not know the temperature is enough to start the regeneration
- if sensor for ambient temperature is not working, regeneration won't start, seen as 00 degrees or two dashes on the display usually
- throttle body error with the air flap before the intake manifold - the flap may be stuck or damaged and is clogging the dpf

Click image to enlarge

Hi Georgi,
I feel your pain friend. I have been there. As you have ascertained, the force regen is treating the symptoms, not addressing the cause.

Before anything else, have you had a High Pressure Smoke Test done?
A leak in the induction system is the most likely cause. Must be high pressure.

Also Dolphinboy had similar symptoms and may wish to chime in. He had a peculiar issue which sounded similar.

Notes below.

Good luck,

Matt





Here is my list of the usual suspects:
DPF associated issues
- turbo oil drain mod . (unlikely to be the cause in itself to the degree you are talking about)
- a leaky air duct or maf sensor (leak of the inlet air), if the maf sensor does not work well or an air duct is cracked behind the maf sensor, not enough air may enter, but more fuel - which makes more carbon deposits and clogs the dpf; the air line from the filter to the turbo (induction hose); turbo hose leak (bringing air from turbo to engine) (most likely)
- over-fuelling due to leaking fuel injectors (can trigger check engine light) - also injects more fuel and can clog the DPF. ( "A drippy injector" I have heard this throerised as a cause but never proven)
- DPFs require a special low-ash oil C1 instead of A5. (yes but surely not using the wrong oil)
- leaky turbo oil seal. (could be).
- faulty EGR valve - pumping excess crankcase vapor into the exhaust (could be but rare).
- exhaust gas temperature sensor faulty - would not let regeneration start.... (not sure on this - again unlikely and there is a sensor on the EGR gate which reads the degree to which it is open. It would to have an actual hole in the gate for this to be the cause. - those are the exact words from a LR Chief Tech a few years ago)
- faulty glow-plugs - also DPF-deadly - because they cause the engine to run too rich on start-up or a fault of glow plugs prevents the regeneration to start. (not sure about this)
- differential pressure sensor error (could be - see notes below* on finding the correct one - the wrong one will trip you up - these are notes I borrowed from someone else - not my direct experience. )
- if the thermostat is faulty, the computer would not know the temperature is enough to start the regeneration. (not sure / never heard of this - )
- if sensor for ambient temperature is not working, regeneration won't start, seen as 00 degrees or two dashes on the display usually(not sure / never heard of this - )
- throttle body error with the air flap before the intake manifold - the flap may be stuck or damaged and is clogging the dpf . (this is sensored, presumably throw up another error code and affect performance)


*DPF sensor The part no is LRO23134 this seems to be directly linked to 6g9n-5l200-aa dp1000 (USE THIS ONE), the replacement I got was 6g9n-5l200-ab Dp1200 as was told this superseded it, this may not be the case and could also be why the voltages are higher. To confirm if anyone needs to replace the sensor then only use 6g9n-5l200-aa dp1000
Whilst the AB is a direct replacement from a Ford perspective they have very different tolerances and it will falsely report the DPF as full in a very short time.




. 2012 L322 4.4 TDV8 AB low mileage - a peach
1986 V8 Defender 90 County ex-Swiss Army - Red everything....

My preferred Independent: Roy Hardy. R & B AUTOS LTD, 20 Brook Road, Wimborne, Dorset, BH21 2BH 07500 866775‬ (Ex LR Chief Technician)

Last edited by Range Rover L322 on 18th Aug 2024 11:12pm. Edited 3 times in total

Has the air intake donut been cleaned and the 4 hoses checked for leaks?
If the EGR valve was always open then I would expect air flow discrepancy faults due to unexpectedly low air mass passing through the MAF, although if open just a little then maybe not enough to trigger a plausibility fault.

Hi Matt, Graeme,
Based on what I read on forum I would have started with checking hoses for leaks and cleaning the donut with brake cleaner. I already cleaned the MAF sensor myself as it was the easiest to start with.
But the mechanics answer with "do not read on forums" when I try to "guide" them on their research. I suppose the guys feel offended that I meddle but in the same time I feel like they are not really troubleshooting and attacking the problem without research with replacing parts on suspicion from faults.
I haven't heard of any such smoke test being done in my city but I will have to check that further probably.
Thanks! l322 2011 4.4 TDV8 Autobiography Black
l322 2007 3.6 TDV8

Not sure that ERG valve error is correct as the values for commanded and actual are only a few % different - what diagnostic kit is that? Also an EGR error of that amount would not only throw it's own fault code but the car would be nealy undrivable with very hesitant and uneven throttle response. I assume the mechanics have done a full and in depth fault scan? Do you have a GAP IID tool to do your own? My money would be as other have said - faulty pressure differential data and / or bad intake air leak. 2012 TDV8 Vogue (L322)

Hi Jay,

Can you tell me what you think is the correct % for the EGR readings? I am not familiar and the mechanic told me something like "if it reads 100% means it is open 100% of the time so faulty - change it".

Regarding undrivable - but some guys delete EGR at all, that should not be felt that much, shouldn't it?

About GAP tool, honestly I put off the purchase of this tool as I am not that sure it is worthy.
I know the majority of forum members have high esteem for it, but when I did forced regen with the mechanics I realized that their chinese tool for 300 pounds can do it and the GAP tool for 350 can only monitor. So far not sure what to buy.

In the meantime I rely on feedback from the mechanics as on the picture above.

Thanks  l322 2011 4.4 TDV8 Autobiography Black
l322 2007 3.6 TDV8

The difference between actual and commanded are all that is important. 3rd party diagnostic software ( inc GAP IID) is not 100% reliable at correctly interpreting all data streams. EGR delete operations involve shutting the EGR gasflow and not having it open. The GAP tool doesn't just monitor and it can let you change and program featres and it also has a function to do forced regens. You also can monitor and record the car while you drive to see how systems respond over time and not just rely on a mechanic giving you a snapshot at the garage. Unfortunatley it sounds like you have no option but to be at the mercy of what the garage tells you and is able to do to fix this issue - good luck  2012 TDV8 Vogue (L322)

I will buy a tool, that's for sure. Just not sure which to choose yet. By the way I saw that in the threads here and on GAP website, there is no forced regen for l322 at least in the non-pro version, and the pro is at the price of a RR itself

Otherwise, I am at the mercy of my lack of free time to start learning on the car in front of us which is probably not the best idea as well It is not opel vectra from 1995 after all, when I open the bonnet I feel somewhat intimidated  l322 2011 4.4 TDV8 Autobiography Black
l322 2007 3.6 TDV8

You don't need the pro version for full functionality inc forced DPF regens which were enabled by default in a recent update so the info you are looking at my be out of date. Unless you have a trusted knowledgable indy or have the time to spend doing DIY diagnostics and repairs these cars will present significant challenges to ownership. Not sure what the emissions legislations are like in Bulgaria but another option may be to have the DPF and EGR systems 'deleted'. 2012 TDV8 Vogue (L322)

I had very similar symptoms. And I turned out to be a split left hand side inlet manifold which was causing the problem. It was very difficult to spot,as there was little evidence of oil misting etc in the area of the split .

JayGee wrote:

You don't need the pro version for full functionality inc forced DPF regens which were enabled by default in a recent update so the info you are looking at my be out of date. Unless you have a trusted knowledgable indy or have the time to spend doing DIY diagnostics and repairs these cars will present significant challenges to ownership. Not sure what the emissions legislations are like in Bulgaria but another option may be to have the DPF and EGR systems 'deleted'.

In Sofia they are banning diesel under euro 5 this winter so with the 4.4 I am fine but I can't use the 3.6. Besides honestly I am not against maintaining complicating but cleaner vehicle, just lamenting the knowledge of the so called "knowledgable indys"

I will check that about the gap tool update, probably got old info, thanks! l322 2011 4.4 TDV8 Autobiography Black
l322 2007 3.6 TDV8

Dtech wrote:

I had very similar symptoms. And I turned out to be a split left hand side inlet manifold which was causing the problem. It was very difficult to spot,as there was little evidence of oil misting etc in the area of the split .

Georgi wrote:

Hi guys,
- faulty glow-plugs - also DPF-deadly - because they cause the engine to run too rich on start-up or a fault of glow plugs prevents the regeneration to start

Hi Stuart,

Being not a mechanic what you wrote makes sense to me. But I read it at least several times on other people's post and I think I watched a mechanic saying something in the line of - the system does not start regen if it senses the faulty glow plug.
Either that is false or if true is some unnecessary prerequisite for regen that is engineering mistake. l322 2011 4.4 TDV8 Autobiography Black
l322 2007 3.6 TDV8

All the comments above are valid and useful.

I can only repeat a High Pressure (HP) smoke test is the first thing to do. This is the standard "go-to" test when a DPF is filling too quickly on an L322 - a leak in the system is the issue 9 times out of 10.
It is not worth doing the other work until this has been eliminated as a cause.

Every diesel garage will have Low Pressure (LP) smoke test equipment. Good ones will have HP as well.

I hope that's some help!

Good luck.

Matt 2012 L322 4.4 TDV8 AB low mileage - a peach
1986 V8 Defender 90 County ex-Swiss Army - Red everything....

My preferred Independent: Roy Hardy. R & B AUTOS LTD, 20 Brook Road, Wimborne, Dorset, BH21 2BH 07500 866775‬ (Ex LR Chief Technician)