The AA swapped both AFM sensors around and with a new one I had bought, and found no fault with either of them.
There is a possible air leak after the AFM 1. (closer to the bulkhead as you look at the engine bay from the front)
Need to remove lower engine pans to investigate and see if its a cracked pipe, or could be something else, hopefully not the inlet manifold or anything as expensive!

On idle the air flow readings on each AFM sensor were quite similar in the 8 mark or so. When revved, the faulty side would remain low, and the proper working side would increase air mass to 50's etc... so when idling again, it would be ok. This happened with any of the 3 AFM's we had swapped around in the two places.

The full fault report is here:

AA Patrol found the following fault code/s:System : Engine control - 7M9 / Diesel EDC 17CP11.2 Status :P006A - Mass or volume air flow circuit. Error Message : Malfunction. Fault pending. Status :P00BD - Air-mass meter or air-flow sensor A. Error Message : Mechanical fault. Fault pending. Status :P1247 - Boost pressure control low pressure level. Error Message : Malfunction. Error sporadic. Status :P0235 - Turbocharger boost-press. sensor A. Error Message : Improper operation. Error sporadic. Status :P010C - Mass or volume air flow circuit. Error Message : Malfunction. Fault pending. Status :P0102 - Mass or volume air flow circuit. Error Message : Malfunction. Fault pending. Status :P00AA - Intake-air temperature sensor 1. Error Message : Voltage above threshold. Error sporadic. Clear faults and run up with live readings. Sounds like choking or leaking at boost pipe. Engine Oil Level Ok. Coolant Level Ok. Advised check on turbo pipes for leaks or collapse and also for EGR sticking. Customer going to contact garage to see if repair feasible.

I looked on YouTube and thought of making my own smoke machine. PowerfulUKltd made a video and replied saying he thinks it's leaking pipe too.
&lc=UgzrvR1lq59kVdelfHl4AaABAg.9JQ9YN1Zzd39JQGKPphVLn

Question is, if I make my own smoke machine will take me at least a week.
How much would most garages charge for a smoke test to see where the possible problem is?
Would you take this to any reputable garage, or a RR specialist? The car has always gone to a RR specialist, but it's getting expensive now!! We haven't skimped on repairs or maintenance ever, but it it is getting hard in this pandemic now, and I think the specialists maybe overcharging?

What are your thoughts?
Cheers!

I had the Restricted message pop up last week, did a scan with my GAP tool and was the MAF on bank B. Ordered a new one and presto fixed, erased the codes and nothing has popped up since. I did have a crossover pipe leak issue a few years back and that was a real pain to solve as its well hidden at the rear of the engine. First port of call is get your hands on scan tool, this will save time and cash! 2018 Telsa MS
2012 Range Rover Sport HSE+
1990 Porsche 944
1985 LR 90 Soft top V8

Already got the fault codes from the AA report...?
It's not the MAF.

A local garage has said they will charge £60 (I presume plus VAT) to undertake a diagnostic check, and this will include a smoke test if required. For this, they will 100% identify the issue.

From there we can see what's wrong with it and then ponder the fix.
Sounds OK, right?

£60 is reasonable for a scan and smoke test.
Is that Rovertune you’re using? Visitor from fullfatrr.com
* GONE. 2012 RR Sport HSE SDV6 Orkney Grey. Now being piloted by RRSTDV8
* GONE: 2011 4.4 TDV8 Full Fat. Amazing piece of kit.
* Current. 1974 Lightweight 2.25L petrol. Old skool
* GONE. Freelander GS TD4 Manual MY2013. Orkney Grey with privacy, cold and clearview packs, armrests (a must!) and a spoiler.
* GONE. Range Rover Classic '93 200Tdi Factory fit
* 1949 80" in family since 1975

To be honest, I'm very miffed with Rovertune.
Maybe it's just the car, everytime its in there we spend over £1k extra than we had envisaged.
I dare not think how much Rovertune would have charged to check.

Easier than building my own smoke test machine too, that I was almost looking forward to, until SWMBO said I had better things to do lol.

So, now the car is going to a well respected garage in Langley... that the AA recommended, and coincidentally is where my father takes his cars anyway. It goes in on Tuesday.

The garage (after taking ages!) have diagnosed the error as the Turbo Secondary Shut Off Valve (TSOV).
It's jammed shut, so they opened it and test drove and sorts the problem out. So they will now replace. Awaiting a quote for parts and labour.
Does anyone know how much this normally costs please?

In addition, I will ask them if they can do this mod too, a bypass valve for the TSOV...

TSOV replaced and all seems OK now with the RRS.
I didn't do the bypass as garage said its a completely different job and I'll need to rebook it in.

Cost me £300 all in, diagnosis, labour, and parts.