Afternoon all,

Hoping someone with more technical know how then me can help with the error code I have.

GAP IID gives me: P0046-77 (2F) Turbo/supercharger boost control solenoid - circuit range / performance - mechanical failure - commanded position is not reachable

The car intermittently drops into Restricted Performance with the red triangle.

I tried to check the live data on “commanded boost actuator control - Bank 1” and the same for bank 2. Bank 1 is 0% and if you boot the car hard it jumps to 100%, no variation between where as bank 2 is fluctuating depending on how hard the engine is working. This may be nothing to do with the fault, I was taking a pun at which live data may be useful. I’m assuming it’s a stuck/faulty actuator?

Any advice on where to go next, where to locate any potential faulty items, and what to try next would be great.

Many Thanks, J

Faults shown are normally a symptom and not the cause.

I'm assuming it's a 3.6?

If it's a 4.4 TDV8, the turbos are different. One is fixed and one is variable. One works 1,300+ and is variable, the other doesn't kick in until 2,200+, so they will perform differently. 2015 Range Rover Autobiography 4.4 SDV8

It a 4.4 TDV8.

I also had the donut off at the weekend, cleaned everything up and replaced the 4 intake rubber hoses, and cleaned the MAP and MAF sensors

Any loss or irregular boost from either turbo? When does it go into restricted performance? E.g heavy acceleration?

Next thing I'd look at is the plastic union between the throttle body and the intercooler hose. If it's loose or there's sign of soot in the vicinity, temporary fix it to see if it solves the issue (just wrap gas spec PTFE or silicone tape around the throttle body and refit tight).

It's very rate for a 4.4 TDV8 to experience any form of turbo issue. 2015 Range Rover Autobiography 4.4 SDV8

It’s really intermittent. I took it for a run to try and diagnose it. I drove it steady, booted it, engine braked and it wouldn’t fault, then steady cruising at 55mph on the dual carriageway and it faulted.

I think there is more lag than there used to be, it seems a bit slow to respond when you accelerate.

I had the throttle body apart and cleaned it all up, and checked the large intake hose that attaches to the throttle body and that all seemed ok.

I’m pretty baffled. How you drive it, engine temperature no consistency in the error.

I assumed it was a sensor to begin with as I think it faults when the ECU does its status checks

The symptoms are similar to a small split in one of the charge air hoses or a leaking union, are you able to get it smoke tested? - not the usual low pressure smoke test, needs to be around 1.5bar.

I’ll ring round and see if there is somewhere that can smoke test it.

Which pipes are the Charge hoses?

The two big hoses at the front of the engine bay.

Sometimes you need to remove them and give them a good squeeze and inspection to find a split.

I once found one where the split was only visible when squeezing it in the hand. 2015 Range Rover Autobiography 4.4 SDV8

Charge air hoses are anything after the turbos, air intake hoses are anything before them.

Ok, thanks for all the advice, I’ll strip some more hoses off and inspect them.

I’ll make some calls about smoke testing tomorrow too

Bookmarked this as it is suspiciously similar to the problems my 4.4tdv8 has.

I've booked mine in for a inlet smoke test on Friday in the hope to find something split. 2010 L322 Autobiography Black Edition
1975 Land Rover

Keep us posted on how you get on with the smoke test, I’d be interested to know what they find

Have you checked if the CSOV for the second turbo moves freely. There is an upgraded part.

Which is the second turbo, and what is the CSOV? Is it the actuator at the bottom on the near side of the engine bolted through the radiator housing? If so Yes. I had it off and cleaned it up etc when I swapped the alternator, belt and tensioner a couple of weeks ago.

Sounds like you found it. Charge air shut off valve.
If yours has a nut on the actuator rod then it is original. Modified part is LR033284 but if it moves freely then I don't think it would help your problem.