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Retroanaconda

Member Since: 04 Jan 2012
Location: Scotland
Posts: 2635

P0401 - EGR flow insufficient

Documenting this here to hopefully help anyone else who has the problem in the future.

2020 Defender 110 D200 3.0 litre
73,500 miles

Car developed a slight judder and hesitation under low speed acceleration a few weeks ago. No other symptoms, then a week or so ago the engine management light came on. The most obvious error code is as above, full diagnostic readout below. Light was cleared by LR Assist but came back on a few days later. A further few days on it’s gone out again, but the judder/hesitation remains.

Click image to enlarge

It’s being (eventually) picked up by LR Assist on Friday to go to the dealer for repair. I’ll update with what the fix is, though apparently they’ll not be able to look at it until January.

Current suspicious centre around either a blocked EGR cooler or a dodgy sensor misreading flow rates.

12th Dec 2023 9:49pm

lightning

Member Since: 23 Apr 2009
Location: High Peak, Derbyshire
Posts: 2690

There's a few random faults there.
"Wiper motor module, component internal failure" Do the wipers still work okay?
"Apix display link, front display circuit open" What's the chance of repairing that on your drive.

l hope the vehicle is still under warranty!

Please keep us updated.

14th Dec 2023 7:49am

Retroanaconda

Member Since: 04 Jan 2012
Location: Scotland
Posts: 2635

Yes it’s under the factory warranty until the end of this month. I’ve no idea what the other faults were for, there’s nothing wrong with the screens or wipers. Could just be spurious ones from missing bits as mine is a base spec model.

LR have been back on, they say that it’s been fixed and road tested okay. The MAP sensor was at fault.

I will update once I’ve picked it up to confirm all is well.

20th Dec 2023 9:30pm

Retroanaconda

Member Since: 04 Jan 2012
Location: Scotland
Posts: 2635

Picked the car up today, the fault did not reoccur on the 130 mile drive home so I’m hoping all is well. Will update again if it is not!

23rd Dec 2023 5:37pm

Moo

Member Since: 01 Oct 2021
Location: UK
Posts: 1327

That's good

Are you planning to renew the warranty? Eiger Grey MY23 D250 SE with bits. Known as Noddy.

23rd Dec 2023 6:08pm

Retroanaconda

Member Since: 04 Jan 2012
Location: Scotland
Posts: 2635

Yes, I have done so. I’m covered for another year or until I hit 100k miles, whichever comes first.

23rd Dec 2023 6:26pm

Ianh

Member Since: 17 Sep 2018
Location: Essex
Posts: 1970

Keep an eye on slight hesitation just after changing gears from 1 to 2 and 2 to 3, it’s a classic EGR issue.

23rd Dec 2023 9:15pm

Retroanaconda

Member Since: 04 Jan 2012
Location: Scotland
Posts: 2635

Thanks. What causes it?

23rd Dec 2023 10:18pm

Ianh

Member Since: 17 Sep 2018
Location: Essex
Posts: 1970

A sticking EGR. They do wear out / get gunked up with soot and oil. At 73k yours has done well and they do need replacing/ cleaning at some point. Now I’m an old an old defender 2.2 owner, but undertake services on lots of vehicles, and on modern diesels EGR’s are not a fit and forget item. It all depends on your normal driving. If its lists of short journeys at low speed they do gunk up and need replacing or cleaning.

23rd Dec 2023 11:53pm

Retroanaconda

Member Since: 04 Jan 2012
Location: Scotland
Posts: 2635

Ah I see.

I did monitor the demanded and actual positions of the valve during driving a week or two back and they matched up well, suggesting the valve was moving okay. However I’ll keep an eye on it and if the issue returns perhaps have a look into the system and see if it’s clogged up.

The vehicle does a lot of long drives, so that at least shouldn’t be an issue.

24th Dec 2023 8:20am

Retroanaconda

Member Since: 04 Jan 2012
Location: Scotland
Posts: 2635

So it wasn’t fixed, issue came back after a few hundred miles. Now records a different error in the ECU (as below). No engine management light yet though.

Click image to enlarge

29th Dec 2023 10:00pm

90dv

Member Since: 29 Jun 2011
Location: Cumbria
Posts: 36

Which MAP sensor did they replace?

I suspect they replace in inlet manifold pressure sensor.

The P006B code is related to the exhaust manifold pressure sensor in the exhaust manifold. It has a very narrow pipe that can become blocked with soot.

It also logs the EGR fault eventually as it isn’t able to determine the high pressure EGR has opened as it isn’t able to see the pressure difference in the exhaust.

30th Dec 2023 8:06pm

Retroanaconda

Member Since: 04 Jan 2012
Location: Scotland
Posts: 2635

Interesting, thanks.

Yes they did replace the MAP on the inlet manifold, apparently (if you believe the warranty/service invoice) the circuit tests suggested it had failed internally.

I’ll have a look at the exhaust manifold next week, if I can figure out how to access it. Suffice to say finding things on this engine is a bit harder than on the old Tdi!

30th Dec 2023 9:19pm

Retroanaconda

Member Since: 04 Jan 2012
Location: Scotland
Posts: 2635

Here is their report. Their road test was only 20 mins up the motorway which isn’t enough time as the fault can go much longer between occurrences.

Click image to enlarge

30th Dec 2023 9:21pm

90dv

Member Since: 29 Jun 2011
Location: Cumbria
Posts: 36

That is the part number for the one in the inlet manifold. The exhaust one is actually just in the 90 degree bend just after the turbo.

Hope they get it sorted for you

31st Dec 2023 8:46am

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