XC70: Engine Turbo issues

[Spriteracer]

Morning all. I need a bit of help please and apologies if this initial post is a bit lengthy.
I have a 2009 model XC70 with D5 and Polestar upgrade. Mileage approx 221k

The turbo was replaced by Volvo in 2019 (about 80k miles ago) Swirl flaps and actuator have been replaced and calibrated. A Volvo independent had a look at the boost pipes and couldn't see any leaks, albeit without a smoke test. EGR is clean and moves, Air mass device swapped for a known good one.

For the past few weeks it goes into limp mode intermittently with codes P029900 turbocharger under boost and P23484 turbocharger over boost at the same time. If the codes are cleared they can reoccur after 50 yards or 50 miles and can come and go driving along. The dash message is "engine service required - urgent"

Volvo have advised after two visits to diagnose, that another new turbo is required at a cost of £3k+ but are not 100% sure of the exact issue. They say all the relevant sensors are within parameter. Patently this is not realistic as it is probably more than the car is worth. Even an independent is likely to charge £1500- £2,000. The car is too good to scrap, but not saleable like this.

Does anyone have any further suggestions to offer, and can someone point me at a "how-to" to remove the turbo and it's controller myself to inspect. I'm reasonably mechanically minded and have built and run my own race car for many years.

Many thanks for any suggestions.

[Simmy]

did they fit a new actuator with the new turbo? also check the inter cooler for any bowing or splits check all associated pipe work including any rigid pipe work which may have broken away from the fixing a smoke test will aid these tests its not unheard off for the gears in the actuator to fail.

[100K+]

I have a 2015MY V70 D5 which has an infrequent ECM-P029900 under boost condition and a over boost condition - but a different code to you. They have never thrown a MIL. If I never exceed 2000rpm they would never return, and such is the torque staying under 2000rpm is no great difficulty. My initial diagnosis was the two turbo control values, located in my car on the RHS ( facing the car) at the back of the engine near the battery box. They are the size of a match box. One has 3 rubber pipes leading to it (IIRC the left and right run to sections of the intake system the centre one runs down to the larger turbo waste gate) the other has an electrical/vacuum operation?? and only 2 pipes one runs to the inlet manifold top, the other to the air flow diverter ( it looks like a waste gate actuator) which changed the air flow to the larger turbo from the small one.
I have read my issue is with the 2 pipe unit.
When I originally looked at this problem ( several years ago) replacement parts were three figures, recently I have seen the bits on ebay and similar for under £30.
Both bits are used across many V/S turbo cars. Si Robb has 2 or 3 videos on Utube about how to clean each unit- so they have been around some time..
Good luck Cheers Bob

[Spriteracer]

100k+ many thanks. I will have a look at the parts you suggest although I would have hoped the Volvo main agent would also have done so...

[Spriteracer]

Simmy, thanks. As far as I recall they replaced the whole thing. I do recall them mentioning broken gears, and the fact that they will not just replace damaged parts - such as the actuator even if the turbo itself is still ok.

I will check the intercooler and pipes again even though both Volvo and the indy have apparently already done so. I seem to remember a youtube video on how to make a smoke tester. Commercially available ones seem too expensive for a one-off use.

[Rcdean]

I've had this problem before, was very intermittent at first, just thought it was gearbox being lazy and not wanting to shift down.

Was only after doing a scan and getting the over and under boost faults that led me to looking at the turbo system.

One thing that I noticed was that both errors logged at the same time which made me suspect electrical.

This pressure sensor will need replacing,

Bosch 0261230293 Pressure and Temperature Sensor https://amzn.eu/d/07muuuPf


It's located on the intercooler on the bottom right hand side where the pipe comes in it

Not the easiest to change if you've got big hands.

[Spriteracer]

Rcdean, That is really helpful thanks. My two codes also occur at the same time so hopefully a new one will solve the problem. Ordered so fingers crossed !