Good luck with the fix - I was in contact with someone else who fixed his with Sikaflex marine and it lasted about a year, possibly due to being a bit more flexible?
Much as I moan about LR quality and reliability and as someone who's wallet got a kick because of this problem, I can't agree that it should be a recall. Mine lasted 12 years and 144K miles before it failed which looks like the norm - i'd be more than happy if I thought all other LR components lasted that long!

Thanks gilesharrison and cass for information.

After some research I believe the only long term solution would be a true fusion weld. It is unlikely that adhesive bond can hold over long time with high pressure air behind it.
I conclude that the air intake manifold (valve cover also call rocker or cam cover) is made from type glass - reinforced version of nylon (PA). The melting point of glass reinforced nylon is 269 degrees Celsius which is much more than other plastics (PE, PET, PC, PPE etc.) I will get some powerful plastic welder with precision set up and attack the crack this way:
1. Clean area
2. Grind out a v-groove down the crack in the manifold with heat gun bit.
3. Weld the crack with nylon (PA) welding rod to patch the crack.

It would be ideal to attack also the backside of the crack but it would need to remove the manifold and in such case better to bite a bullet and replace it.

Wow. Good luck. I don't know anything about plastic welding but you definitely do.

Incidentally, the manifold replacement is not as big a job as suggested. The air con doesn't need de-gassing, and the engine does not need to be lifted. The rear injector can be removed by splitting it below the solenoid. Don't get me wrong, it's fiddly and time consuming but that's all. I could probably do it in about 6h (second time around)!

Thanks.
I'd like to share my solution to the issue. Eventually, I used Leister Triac ST heater gun with PA (nylon) settings and PA 6.6 welding rod. I did not have previous experience welding plastics but basically it is the same like any other welding. The gun can do really great job (AT version is better) with all sort of plastics but most importantly PA. My workshop manual says to de-gas and raise the engine up. RR is LHD, although I agree degas could be avoided. I did not know about the trick with the rear injector.
I will let you know how it goes as welding was success so far.

Good effort. I hope it lasts well.

I wish I’d thought of that - the welder costs less than a new manifold never mind the labour involved.
Could be a canny sideline for an independent mechanic!

This is the exact same fault I've got. I've sprayed soapy water on the manifolds but I don't see any bubbling.

What really puzzles me is the infrequency that it faults apart from one particular location. If I leave work, I turn left onto an estate. For the first couple of months of ownership, it would always fault in the same place on that particular stretch of road, no matter how I drove it. More recently it doesn't do it at all, save for the very rare occasion.
I lived at the top of a big hill and it used to fault around 3/4 of the way up. Again, whether heavy footed or not. It's been two weeks now and no faults. When it does fault, it will fault every day for a week or so. It even faulted as I pulled off the driveway with very little acceleration. Yet other times, I can really push it and it won't fault.

I bought this car to replace my ageing TD6 and to tow a twin axle caravan. I'm frightened to tow it as it faulted a lot with the van on the back and one heart stopping moment last year, it almost came to a standstill on a steep hill. Foot flat to the floor and doing 10mph with traffic queueing behind us!

I have had a smoke test but it only detected a hole in the air box to turbo plastic trunking, which I replaced. Didn't cure the fault though.

I have the IID tool. How do I test the resistance of the MAP sensors? 2010 MY Vogue SE TDV8 3.6 Stornoway Grey- fully loaded

Swap the MAP sensors over and see if the fault remains on the same side on the engine.

I’ve done that. Also replaced the top hoses with silicone even though there were no splits 2010 MY Vogue SE TDV8 3.6 Stornoway Grey- fully loaded

When I had my manifold crack, the error regularly used to happen up one certain hill. However, other times it seemed temperature dependant. Like when it was cold, it was less likely to give the error. Hot weather, or when the engine was hot, seemed to happen more.

Did you just change one of the manifolds?

What is your trouble code when Limp mode happens?

Is it P023d-22 -
(Manifold absolute preassure - turbocharger/supercarger boost senzor A correlation - general signal failure.)?

This is most often a wiring issue or an air leak.

Check:
Intake air system fault (cracked manifold, turbo intercooler houses...)

Turbocharger mechanical failure
Intake air temperature sensor failure
Mass air flow sensor failure
Manifold absolute pressure and temperature sensor failure
Exhaust gas recirculation sensor failure
Turbocharger actuator position sensor failure

Andy wrote:

This is the exact same fault I've got. I've sprayed soapy water on the manifolds but I don't see any bubbling.

What really puzzles me is the infrequency that it faults apart from one particular location. If I leave work, I turn left onto an estate. For the first couple of months of ownership, it would always fault in the same place on that particular stretch of road, no matter how I drove it. More recently it doesn't do it at all, save for the very rare occasion.
I lived at the top of a big hill and it used to fault around 3/4 of the way up. Again, whether heavy footed or not. It's been two weeks now and no faults. When it does fault, it will fault every day for a week or so. It even faulted as I pulled off the driveway with very little acceleration. Yet other times, I can really push it and it won't fault.

I bought this car to replace my ageing TD6 and to tow a twin axle caravan. I'm frightened to tow it as it faulted a lot with the van on the back and one heart stopping moment last year, it almost came to a standstill on a steep hill. Foot flat to the floor and doing 10mph with traffic queueing behind us!

I have had a smoke test but it only detected a hole in the air box to turbo plastic trunking, which I replaced. Didn't cure the fault though.

I have the IID tool. How do I test the resistance of the MAP sensors?

Yes that’s the fault code.

I’ve swapped the MAP sensors and it’s still Bank A.
The top hoses have been replaced with silicone as a precaution.

The actuators seem ok but I’ve got nothing to compare them to.

EGRs have been mechanically and digitally removed.

I can’t see the lower hoses to check. I need a couple of dry days so I can get out on to the drive and strip it down.

I have thought wiring in the past and I hope in some ways it is that. 2010 MY Vogue SE TDV8 3.6 Stornoway Grey- fully loaded

Rule out faulty turbo actuator with your IIDtool.

Select Live values and compare Command boost actuator control banks 1/2 with Boost pressure actuator banks 1/2 and create log when driving.
Try monitor the turbocharger actuator position and command the actuator to 5% PWM, then 95% PWM in 5% steps (unfortunately this function is not always working (not working on my 2008TDV8; IIDtool). Check the results. There should be a smooth curve between the minimum and maximum values. If not, install a new turbocharger.

How do I increase by 5% whilst driving? Once it’s data logging it can’t be changed can it? 2010 MY Vogue SE TDV8 3.6 Stornoway Grey- fully loaded

That's supposed to be done when idling.