I have a 4.4TDV8 with 99k and I’ve had the P0401-00 error come up twice in the last 500 miles. It’s easily cleared with the Gap IID tool but I’m mindful that clearing the error is not solving the problem.

I understand that the EGRs need changing out on these engines around the 100k mark and that to do so will be a pig of a job. However, before I leap to changing out the EGRs, my question is:

Should I look into other solutions as a sort term option to prolong the longevity of the EGRs?

Thanks in advance everyone! Andy

2010 4.4TDV8 Vogue SE in Santorini Black with Ivory interior
2017 Audi SQ5 3.0 V6T Quattro in Volcano Red
2001 Audi Allroad 2.5 TDI manual with low-range in Highland Green. Currently SORN whilst undergoing some serious restoration!

Last edited by Ajmngn on 9th Jun 2023 8:03am. Edited 1 time in total

clogged egr cooler. A lot of work to remove and clean.

Quote:

EGRs need changing out on these engines around the 100k mark

As a possible “quick win” you could an egr cleaner spray? One where you spray into the intake as the engine is running…

It’s never going to be as good as removing the egr and cleaning… but may do enough to resolve your issue.

Also, pop the egr pipe that goes into the intake manifold. It’s a simple 5 bolt removal job. You may find that’s blocked due to the usual crud build up in the intake. Again, a possible easy fix…

Lastly an egr blank and delete could be another less expensive option? Currently driving: 2012 L322 SE Overfinch 4.4 tdv8

Past rides:
2014 Audi Q7 3.0d (good riddance)
2010 L322 Autobiography 5.0 Supercharged
2011 L320 HSE 3.0 sdv6
2014 Jaguar XF-RS 5.0 supercharged
2007 BMW 535D
2005 Mini Cooper S

https://www.fullfatrr.com/forum/topic59478.html

If you want to consider the egr delete (or looking for a garage to help) then contact Martin at Dartford Automotive… he’s potentially not too far from you. Currently driving: 2012 L322 SE Overfinch 4.4 tdv8

Past rides:
2014 Audi Q7 3.0d (good riddance)
2010 L322 Autobiography 5.0 Supercharged
2011 L320 HSE 3.0 sdv6
2014 Jaguar XF-RS 5.0 supercharged
2007 BMW 535D
2005 Mini Cooper S

https://www.fullfatrr.com/forum/topic59478.html

Check for a split in one of the 4 manifold to intake couplers or a split in the intake donut itself. The ECU will close the throttle plate to create low pressure in the intake to increase EGR gasflow but if there is a leak it won't be able to . Any other drivability issues? Are you doing a lot of short trips? 2012 TDV8 Vogue (L322)

GGDR wrote:

Quote:

EGRs need changing out on these engines around the 100k mark

not true on the 4.4 but I think on the 3.6 that may be the case

Ffrr-lover wrote:

As a possible “quick win” you could an egr cleaner spray? One where you spray into the intake as the engine is running…

It’s never going to be as good as removing the egr and cleaning… but may do enough to resolve your issue.

Also, pop the egr pipe that goes into the intake manifold. It’s a simple 5 bolt removal job. You may find that’s blocked due to the usual crud build up in the intake. Again, a possible easy fix…

Lastly an egr blank and delete could be another less expensive option?

FFrr-lover - that's a good idea regarding the EGR cleaner. I've been looking into a product called Revive Turbo Cleaner which seems to get good reviews. These types of cleaners seem much more geared towards turbos than EGRs, so I am interested to see whether they can do anything to help clean the valve, or whether it's just the air intake manifold part where recirculated gases are also being brought in and depositing soot. I've emailed Revive asking for the recommended procedure for doing an application on sequential turbos so I will see what they come back with.

I think that I will avoid anything to do with EGR blank/delete, even if done through the ECU, as there are a lot more threads on this forum warning against it for the 4.4TDV8 than there are of people who've done it with any success. However, I'd be more than happy to hear others' thoughts on this...

I'll have a look at the WM when I get a chance to work out the locations and routing of the key components but I will certainly check out your suggestion regarding the EGR pipe into intake manifold and have a look. Thank you!  Andy

2010 4.4TDV8 Vogue SE in Santorini Black with Ivory interior
2017 Audi SQ5 3.0 V6T Quattro in Volcano Red
2001 Audi Allroad 2.5 TDI manual with low-range in Highland Green. Currently SORN whilst undergoing some serious restoration!

JayGee wrote:

Check for a split in one of the 4 manifold to intake couplers or a split in the intake donut itself. The ECU will close the throttle plate to create low pressure in the intake to increase EGR gasflow but if there is a leak it won't be able to . Any other drivability issues? Are you doing a lot of short trips?

JayGee - some really useful tips, I'll have at look at those pipes when I get the chance to investigate further today. I haven't noticed any other drivability issues - it pulls smoothly and decelerates with no judders; it idles at a constant 800ish rpm; and there's no smoke coming out of the exhaust other than the odd time when booting it over 2500rpm when it clears any oil built up in the second turbo (I don't think mine has had the turbo drain mod but can't be sure unless I'm able to look for something that can be seen fairly easily to show it).

I picked the vehicle up about 2000 miles ago so can't be sure of it's driving history. However, I've been doing a good mix of driving. It does do a few short trips but I also do quite a few long runs and will also take it out for a drive in the week to give it 20 mins or so on a dual carriageway and run it up through the revs using the command shift to really get the engine working and clear out any deposits etc.

I'm minded to give the Revive Turbo Cleaner a go and to try and manually clean any parts of the system that I can access as has been mentioned further up the thread, then just see what happens. However, the vehicle came with a 3 month warranty, that I've already used for a new alternator, and it runs out on 25 May so am minded to take the plunge and use it before the warranty runs out. IThe warranty will only pay £45+vat per hour for labour plus parts, and my local Indy charges £78+vat for labour, so it will cost me the excess of labour charge which would be about at around £400 for a 10 hour job. However, it could be £400 now or a -ton more one the warranty runs out so could well be worth taking the plunge now! Andy

2010 4.4TDV8 Vogue SE in Santorini Black with Ivory interior
2017 Audi SQ5 3.0 V6T Quattro in Volcano Red
2001 Audi Allroad 2.5 TDI manual with low-range in Highland Green. Currently SORN whilst undergoing some serious restoration!

I wouldn't waste money on spray turbo/EGR/intake cleaners. When you have seen the kind of crud that builds up in the intake you will know why a bit of spray will do nothing and it may even damage your engine if it dislodges stuff which is then drawn through the engine. Unlike the 3.6 the EGR valves on these engines are vary rarely a fail item. If you still have a warranty I'd use it to sort this out. 2012 TDV8 Vogue (L322)

If you need a good specialist nr Surrey then highly recommend www.glenrands.co.uk
I won't go anywhere else locally now  Gone to a good home: 2011 4.4 TDV8 Vogue SE Buckingham Blue with Ivory and clear glass = "Rory"
2025MY Defender D350 90 in Silicon Silver on coils
1974 Series 3 Lightweight = "Millie"
Many, many other Landies over the years
My preferred specialist: www.glenrands.co.uk
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Update: looking in the WM ‘Diagnostic Trouble Codes’ leaflet it suggested a number of electrical tests for the EGR electrical actuator leading to a potential change of that part if the electrics are sound.



So I was looking at the EGR valve and cooler system in the WM and couldn’t see anything that seemed electrical, as the EGR valve actuator is vacuum operated. So, I kept looking at other engine bits in the WM. Low and behold, I came across this:

Click image to enlarge

So, a slightly long(ish) update to this long(ish) running saga…

- I got a new EGR valve fitted by Glenrands in Jun 2022 under warranty. That seemed to fix the problem and the P0401. At the time, I was ignorant as to how the EGR system functions and had no reason to question their diagnosis. I didn’t get to see the old valve when removed so have no idea how bad it was. However, what I don’t know (and never will), is whether Glenrands also cleaned the EGR cooler whilst they had free and easy access. To have not submerged it in a bucket of cleaning fluid to dissolve the oil and soot then give it a blast with an air hose or jet wash would have been such an easy and obvious thing to do if the EGR assembly was off the car ad they had the valve off for replacement. If they didn’t do it, I’d be really disappointed in them given where I am today.
- Fast forward 12 months, the P0401 issue is back with a vengeance, after a few very intermittent occurrences over the last 3-4 months. I’ve done a few things to troubleshoot, most notably I took off the exhaust inlet pipe to the EGR valve, along with the EGR valve motor turret to clean the internals with some carb cleaner. I may as well not have bothered as they were fine. I thought it was going to be an oily-sooty swamp, but no. Just a very light dry soot layer on the surfaces and nowhere near enough to prevent free movement of the valve. I cleaned it anyway to be certain, along with the EGR inlet pipe. Bottom line, the valve is fine so no parts warranty comebacks to Glenrands.
- After meticulous Gap tool monitoring of the EGR valve commanded and actual position, EGR cooler bypass position, and throttle commanded and actual position, the valve moves freely and follows normal behaviour the driving. The bypass valve also does as expected, being open on throttle to force exhaust through the cooler and closed when off throttle to bypass the cooler and go straight to the plenum. However, when at a steady cruise, at the point where the EGR valve tries to fully open, if it stays in that condition for more than a few secs then the EGR valve shuts down and closes. That’s what’s clearly triggering the P0401 code because the valve self-protects if it the ECU sees a problem, so the closure of the valve is the reaction to 'sensing' sufficient flow through the EGR. I can drive for miles and all will be fine with the EGR valve part open; it moves almost constantly as you apply various loads to the engine. However, as soon as the EGR valve fully opens, just 2-3 secs in that position is enough to get it to shut off and close for the rest of the journey. I have come to the conclusion that it can now only be one of three things:
1. The EGR cooler is clogged. This is what I believe to be the most likely scenario and one I think I can possibly resolve on the car. I can’t believe it has clogged up again in only one year if it was properly cleaned, hence my comment above.
2. The EGR outlet pipe is clogged. Possible but unlikely, and easy to check/fix.
3. The MAPT sensor is a bit dodgy. Not enough to trigger a separate fault of its own, but enough to not recognise an increase to max exhaust flow to the plenum that should then trigger a part closing of the throttle to balance/maintain pressure. Possible, but the sensor readings in the Gap tool seem fine. I can’t be 100% certain that the sensor isn’t aged enough to work but not at extremes. However, it is giving readings and is clean, so this is possible but unlikely. A new sensor is c.£100 so this is a last-resort option.

My plan:
As the EGR is a closed system (gas in, gas out, sealed unit) am going to get my new endoscope down both the outlet pipe and the valve inlet to see what’s what. If the outlet pipe is blocked, I can clear/clean that easily. If the outlet pipe is clear, I am going to connect my wet hoover to the outlet pipe and, with the inlet pipe removed, the cooler bypass valve manually open to make sure the air is getting sucked through the cooler, and the EGR valve also held open, I should be able to place my palm over the inlet port and feel the vacuum. If I can, that’s good news as the cooler might be restricted but not fully blocked up. If little/no suction difference with my palm then a more aggressive approach might be required.

If I can create a vacuum with my palm, so know air is being pulled through the cooler, I can spray a load of brake cleaner into the valve inlet port with the hoover attached to suck any crud out of the system. I’ve got some of those aerosol caps with really long hoses to get right in there, and I’ll use the endoscope to be certain I’m spraying cleaner into the entrance port of the cooler. It might take a while, and a few cans of cleaner, but I’m confident this could significantly improve flow through the cooler if currently restricted.

If there’s little or no vacuum felt with my palm, I’m going to have to try and clear the blockage another way. The conplan is to pour Vetech DPF cleaning fluid down the outlet pipe and manually open the cooler bypass valve to flood the cooler with the fluid. Luckily, the cooler is the lowest point in the system and it can’t go anywhere else so this should be easy to do without it spilling out anywhere. I can also open the EGR valve to see if the fluid makes it through the cooler or not, I’m just not convinced the bypass valve will create a perfect seal against a fluid. Either way, the fluid will certainly be able to attack any soot deposits in the cooler and should dissolve them if left long enough. After a suitable chance to soak, I can then suck all the fluid back out with my wet vacuum and some hose attachments I have that will allow me to get right down the outlet pipe and inlet port to be sure I get most of it out, along with the dissolved soot. I’ll be able to check this with the endoscope and also by jacking up the front of the car to ‘empty’ the cooler into the valve gallery. Once empty, I can spray some brake cleaner into the cooler via the inlet port with the vacuum on the outlet pipe to suck any remaining oily residue out.

Here’s a few pics I’ve gathered from the WM and the web to illustrate the layout of the EGR and to highlight the exits and entrances to the assembly as described above:

Click image to enlarge

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The issue here is why it's clogging with soot and not how to clean it i.e treat the cause and not the symptom. I wouldn't put anything liquid in the EGR cooler as unless you get it all out there is a real danger of it being sucked into the engine and it doesn't take much to cause a hydrolock. Blocked EGR coolers on these cars are not a common issue - infact this is the first one I've heard about. 2012 TDV8 Vogue (L322)

JayGee, I agree with the symptom/cause conundrum. However, assuming the cooler is partially/fully blocked, chasing the cause isn’t going to unblock it so my priority is to confirm if there is a block and deal with that first before considering causes.

I thought my vacuum idea was a good one as, assuming I went to all the trouble of removing the whole EGR assembly and taking the valve off to access the cooler, it would be hard to test flow through the cooler at that point. Though, it certainly would make it easier to clean and I’d have nothing to lose by doing so if the cooler was out. I don’t want to buy a new cooler as they’re £800+ and it’s unlikely to be damaged so cleaning is certainly the best option.

As for hydrolock risk, check. I already covered that and am very confident I can get the fluid out with the vacuum equipment I have so really not worried about it. Especially as I can lift the front of the car to let gravity drain the cooler and I’ll be able to see with the endoscope if any fluid is still in the valve gallery and suck that out too before firing it up.

Moving to causes, I’m pretty certain that I know the root cause as all the issues I’ve had with this car have been EGR and DPF. I only found out many months after purchase but the previous owner had lived in inner London and that’s where it was also serviced. I bought the car with a stamped service book but no invoices for the works done as the dealer pleaded GDPR. So, I took it upon myself to visit the garage in Kensington that did 4-5 years of work on the car to get copies of the invoices and, it turns out they did a number of forced regens. Whilst I’ll never know for sure, my working hypothesis is that the car was just clogging itself up all the time doing city driving and the owner got fed up with it so offloaded the car after yet another full DPF. I also think the forced regens probably damaged the DPF as there’s no evidence of the garage applying any cleaning fluids to the DPF before regenerating. I think they just used an OBD2 to force it and if the DPF is blocked the pressure can cause the regen to get so hot it damages the monolith. I had to fit a new DPF last autumn after mine blocked with no warning. It got taken off the car for a professional clean in a fancy machine but they couldn’t restore flow so I had no choice but to fit a new one at a cost of £2400 just for the part. I live out in the country and do a lot of motorway miles so I am certain my driving is not clogging the system. My DPF is also regenerating fine now; it’s on its 20th demanded regen since I had the work done; and the average distance between regens is about 400+ miles so I’m pretty certain it’s not oversooting. My MPG is also fine and I’m getting over 30 on a run and not hanging around, so all the indicators are that the engine is running well and the air fuel mix is correct. There’s no smoke out the back and I always use either Shell V-Power or put additive into normal diesel if I need to fill up elsewhere.

When the new DPF was fitted, the car had a high pressure smoke test to check for intake-side leaks and all was well. Whilst that was 6 months ago, it’s unlikely that’s changed. I’ve never had restricted performance issues (touch wood), and I changed out my plenum hoses for reinforced silicone last year. It’s possible there could be a leak with the exhaust to EGR inlet pipe, or EGR outlet to plenum pipe. However, it was all new gaskets when the EGR valve was changed by Glenrands and I can’t see any evidence of a leak.

Anyway, that’s all a very roundabout way of saying that I need to check air flow through cooler as best as I can; try and clear a block if there is one and preferably without removing the cooler from the car; and then monitor to see if that stops the P0401 fault and the MIL light coming on. If there’s a better idea of how to clean the cooler on the car, I’m all ears. I’m willing to take the whole assembly off myself if I have to so I can thoroughly clean it all, but that’s a last resort as it will take a while and I’ll need to buy all new gaskets again, plus the coolant and oil.

I also plan to buy a smoke machine that can be hooked up to an air compressor soon so that I can check my intake for leaks myself and keep an eye on that side of things going forward. There’s some good ones available now for very reasonable money so feel it’s worth the investment. Andy

2010 4.4TDV8 Vogue SE in Santorini Black with Ivory interior
2017 Audi SQ5 3.0 V6T Quattro in Volcano Red
2001 Audi Allroad 2.5 TDI manual with low-range in Highland Green. Currently SORN whilst undergoing some serious restoration!