Hi all. I bought a 2017 RRS SDV6 with 33k miles on it back in August 2021 from a trader down in Kent. Not terribly long after I bought it, out of nowhere I got a DPF blocked message and it went into limp mode. The car came with a 6 month warranty, so I called them and they immediately declared that the DPF wasn't covered...great.

I pulled the codes and aside from the DPF code, there was P0234-77 which is a turbo overboost error. It was listed as intermittent, so I sort of ignored it and focused on getting the DPF unblocked. I found some videos and ordered some DPF cleaner that you spray into the sensor port, which worked. Well, without going into too many details, it took a lot of effort because once the DPF is "blocked" Land Rover want you to replace the DPF, but obviously that's silly on a 30k mile car. Anyway, I found a great video showing that you can trick the car into thinking the DPF has been replaced (I used a hot function on my Autel MS906TS) and that will then clear the message.

So I went back to driving as normal, even took a roughly 1,000 mile trip up to Scotland, and the car did great. A few days after returning, the check engine light came on and it was again the P0234-77. I did some more research and the primary culprit seems to be a sticking throttle. Mine wasn't fully stuck, but I did some work to free it up (there are some posts/videos on this out there) and after clearing the code, I was again good to go for a month or so.

Then the DPF message came up again, no amber, straight to red and "go to dealer" message with limp mode. I did MORE research and it turns out that Land Rover have programmed the car such that when the P0234-77 message is stored, the car will NOT regenerate the DPF and that will immediately lead to a blocked DPF.

Again I went over the engine and after a while I found a broken stem on what I think is the secondary turbo wastegate (I don't have a manual for this car, so I'm not 100% certain this is it but its in the right area.) I fixed that and got it installed and cleared the codes again. But as the DPF was blocked I had to clean the DPF again, and trick the car into thinking the DPF was replaced AGAIN.

Took the car on another roughly 1,000 mile trip to France, and it was all good. Now, 3 days after getting home, the check engine light is on again....P0234-77.

Sorry for the length of the post to get to the question. Does anybody have any suggestions for how to resolve this issue?

To date I've done the following:

1. Freed up the throttle so it moves easily and doesn't stick.
2. Cleaned the MAP sensor
3. Repaired the secondary turbo waste gate arm (I've attached some pictures)
4. Checked vacuum lines (and tested for leakage - all good)
5. Checked for leaks in the turbo pipes

I've seen somebody mention that potentially a split oil separator can cause this. I have found it (right behind the oil filter housing) but when trying to remove it, it was stuck fast and I didn't want to break it (brittle plastic) without having a spare on hand. Has anybody replaced this and can confirm how to remove it?

I kept getting the same code come up (with similar dpf issues), and in the end changed the throttle body and had a software update, which has solved the issue so far.

Well, a few days after I wrote this, I got another check engine light. Same code, plus one for the MAP sensor. I replaced the MAP sensor and that's solved it for now. If I get another error, I'm going to swap out the oil separator, which seems to be a very common problem. Nobody seems to know why for sure. I keep plugging in my scan tool and seeing that the DPF hasn't regenerated in over 500 miles, with no warnings on the dash, with no other error codes present. It seems very odd that JLR have programmed this car this way.

RTMOP:

So the new MAP sensor only kept it running for a day...check engine light on again today, and DPF clogged for good measure. This is getting REALLY old.

New codes:
P0234-77 Turbo overboost - commanded position not reachable
P0069-85 - MAP - barometric pressure correlation - signal above allowable range
P006A-84 (historic) - MAP - mass or volume air flow correlation - signal below allowable range
P049C-00 (intermittent) Exhaust gas circulation B excessive flow detected





Basically, my interpretation is that the ECM can't resolve a difference in pressure between the MAF and the MAP sensor. That is, the engine management is seeing more air in the air intake than was present at the Mass Airflow Sensor. Unless the signal is reverse to air mass, in which case there is a leak somewhere.

I'm going to test all of the TCV solenoids (i.e. N75s) as well as the recirculation solenoid (which is a beast to access) and the other various solenoids. It could be any of them. I found in the manual that this issue can be caused when the recirculation valve solenoid failts, because it fails in the closed position. This causes the primary turbo to overboost, setting the relevant codes.

These were guilty of throttle body issues...

New throttle body, PCM update and an Air Path Setup via diag

I've tested that numerous times and it's functioning as intended. I readapted it twice and there are no issues. I can't tell you how many posts I've found where people replaced this part only to have the problem return days or weeks later.

This morning I tested all the N75s and despite slightly low resistance on one, they all seem fine.

The Charge Air Intake Valve Solenoid, however, seems to be sticking 50% of the time on the bench, and given what it says in the service manual about it, I'm going to replace it. It's less than 50 pounds and would create all the symptoms I'm seeing.


I'll update once I find somebody that has one...only one I can find is the in the Netherlands.

Here's the service manual text on this valve:

The charge air intake valve is attached to a bracket on the front subframe and the cooling pack protector. The ECM uses
the valve to control the bi-turbocharger operation of the turbochargers.
The charge air intake valve consists of a recirculation solenoid and a shut-off valve that are connected together by four
screws and a gasket. The recirculation solenoid controls the flow of air from the compressor of the secondary
turbocharger to the clean air duct of the primary turbocharger. The shut-off valve controls the flow of air from the
compressor of the secondary turbocharger to the charge air coolers.
The recirculation solenoid is operated by a power feed from the EJB (Engine Junction Box) and a ground connection with
the ECM. When it is de-energized, the recirculation solenoid is closed.
If the recirculation solenoid develops a fault it will default to the closed position. In this position an overspeed of the
primary turbocharger will occur. This overspeed is sensed by the MAP (Manifold Absolute Pressure) sensor which detects
the increase in pressure. The ECM registers the signals from the MAP sensor and operates the turbochargers in monoturbo mode with restricted engine torque and DTC (Diagnostic Trouble Code)'s recorded.
The shut-off valve is a flap valve operated by a vacuum actuator. The ECM operates the charge air solenoid to apply and
release the vacuum in the actuator, which opens the valve when a vacuum is present. When the shut-off valve is open
charge air from the secondary turbocharger flows through the valve to the charge air coolers

Yep, I've got the TSB, and as I said, mine checks out fine and doesn't need to be replaced. Have you had one of these in your hands? There is exactly one moving part on the intake throttle body, which is the throttle plate which is controlled by a solenoid. The failure mode is that the plate (which is made of a fibrous plastic material), swells up when bombarded constantly by the soot and oil from the turbo and EGR gases. Once the plate swells sufficiently, it sticks in place in the fully closed position which cuts off the supply of air to the engine, setting the check engine light. Replacing the part will just guarantee that you will replace it again once the new one swells up. That's because, despite the TSB and despite JLR knowing this is problematic, they have not issued an updated part, which they should have done and that part should have a metal throttle plate. It's a FoMoCo (aka Ford Motor Company) part, after all, since this is Ford engine. And had I known that before I bought this car, well, I wouldn't have bought it because as an American I'd rather push my Chevy than drive a Ford, for good reason.

The real fix for the throttle is to file down either the plate itself, so that it no longer makes contact with the walls of the throttle body, or (preferably, in my humble opinion) filing down the walls of the throttle body itself. I say this because it's much easier to file the walls near the axis of the throttle plate, than it is to file the plate itself in that area.

An update on the charge air intake solenoid. I took the car for a long drive yesterday after thoroughly cleaning the solenoid (it was full of dirty oil that was causing the plunger to stick most of the time) and the car felt much better. I actually don't think the secondary turbocharger has been working the entire time that I have owned it (about 5,000 miles and 8 months.) There was so much more power under full throttle at higher revs, it's obvious that the secondary turbo is now actually contributing. That solenoid was closed before and not allowing full power. I'm pretty convinced that this is the real problem. I found the part and ordered it and will replace it regardless when it arrives next week, but I'll keep the old one as a spare. It takes less than 1o minutes to replace it, despite being buried underneath a rats nest of coolant hoses.

So, an update of sorts. I'm still getting "itemporary" P0234-77 errors, but now have P049C as the primary source of the MIL being illuminated. Ran a smoke test and found that it was leaking at the oil separator. Replaced that and it was still leaking in the same place. Replaced the seals between the block and the oil separator (they are cheap) and I can't find any more leaks. The smoke starts coming out the intake on the opposite side. When I plug the intake with a rag, no smoke anywhere so I assume no leaks.

Still getting P049C ("Intermittent" - this is EGR excessive flow detected) and "Temporary" codes for P0234-77 and P0069-85 which is a barometric pressure correlation issue. That makes no sense because the smoke test shows no leaks and the correlation code is usually an air leak. P049C seems to mostly be caused by a super-dirty air filter, but mine is brand new.

Internet search says the EGR code suggests:

EGR volume control solenoid valve
EGR volume control solenoid valve harness is open or shorted
EGR volume control solenoid valve circuit poor electrical connection
EGR temperature sensor and circuit

I guess I'll check the EGR solenoid valve...

Photo below is the smoke test showing the leak at the oil separator.

Having had the RRS for over a year now and suffered the similar problems to you, I want to try and resolve for good.
I keep getting the P0224-77 fairly regularly and despite having filed the throttle body flap so that it no longer sticks, the code returns not long after clearing.
If I don't keep an eye on the soot accumulation, I end up with the dreaded P2463-00 and the red dpf light. I have successfully managed to force a regen using my Autel but something has to be causing the overboost error in the first instance.
I've checked all the things you have and all seems fine.

Have you managed to get a resolution yet?

If I were you, then I would replace the throttle body itself.

In my case, I had over-filed the throttle plate which was then not sealing properly and the charge air/barometric pressure calculation made the PCM unhappy. What's interesting is that the P0234-77 codes ceased immediately, and went away for months, but then the EGR codes started up and wouldn't go away despite all the other leak fixes, etc. I cannot understand why it took months and thousands of miles of driving for the computer to decide that it didn't like the leaks caused by the throttle plate, but that's what it did. I had reset the adaptions several times, but it still doesn't explain it.

A new throttle is less than 300 Pounds. That's what I would do.

I think I might have done the same as you and filed too much off the flap and probably need a new throttle body.
Any recommendations of best place to purchase?
Thanks

I bought one from Maltings Off Road. You need to send the old one back as a core, but they provide a postage-paid label.

Thanks man, I suppose you don't have a part number handy?

LR078546