Apologies for this being so long but I want to be as comprehensive as possible, not least to avoid putting well-meaning forum contributors to unnecessary efforts in trying to help advise me on things that have already been considered.

Car: 2016 VOLVO XC90 2 (256) D5 AWD 224 CV. 115,000 km (71,000 miles) In France

Problems:

1. Significant lack of power. Acceleration is much slower than is usual. Car will only overtake much slower vehicles either on the flat or downhill. Uphill, speed decreases and the gearbox changes down to third while revs climb slowly to a maximum of about 3500 rpm, without changing up a gear. Driving manually makes no difference. If I change up to 4th while uphill, speed drops off.

Even while driving on the flat, If I press hard on the accelerator nothing happens for just over a second. Nothing at all. The revs then rise very slowly.

2. There is a single error read using my OBD2 reader. P2262 “Turbocharger/Supercharger Boost Pressure 'A' Not Detected”

3. Vastly increased fuel consumption. Even with the very lightest right foot (not that a heavier foot makes any difference) I am averaging 12.4 L/100km or 23mpg imperial even when driving at around 90kmh or 60mph. I have not once bettered 11 L/100km (25mpg) since this problem arose 6 months ago.

4. Traces of soot around exhaust pipe tails. Nothing too bad. No obvious signs of smoke.

What has been done:

The car has been at my local Volvo dealer 4 times in an effort to resolve the errors. 2x “diagnostics” including smoke test.

Volvo

first changed the EGR valve and cooler. This did look to be stuck when the vacuum hose was connected to a pump but I was mostly relying on the Volvo mechnic’s word that it had failed.

I was advised that the next step would be to clean the inlet manifold. The quote for this was ridiculous so I removed the manifold and did it myself. It was a bit grubby, but mostly disappointingly clean. The engine inlet ports didn’t look too bad so I left them alone.

The exhaust gas pressure sensor was replaced. There seemed nothing wrong with the old one.

VIDA showed nothing useful, according to the garage.

Last routine service was performed by Volvo last Summer a couple of months before these problems arose.

Me

I cleaned the inlet manifold (see above)

I swapped over the two identical MAP sensors and replaced one that looked slightly damaged with a new part from Bosch. No difference to the error message or symptoms.

Although already done by Volvo, I did a full vacuum circuit test with a pump and manometer. I swapped the two identical turbo control valves and bought a new one, just because it was relatively cheap and I was getting desperate. No change.

I spent days and days researching online for a possible solution and talking to friends, etc.

Second Garage

Diagnostics including road tests were performed by a very highly-regarded Bosch specialist garage in the local large town. This was done twice. Garage had no idea what the problem was and were not happy to proceed further.

Third Garage

This is another local garage with a good reputation. They’ve got plenty of kit (not VIDA) but are also a proper, old-school outfit who want to see happy customers.

The car was in for a week. I was advised that as everything else seemed fine, the problem was 90% certain to be with the twin turbo unit. This garage does not rebuild turbos and I could not find anyone within 100km of me prepared to perform a turbo repair. I was quoted just over €4600 for a turbo unit from Volvo. I bought a remanufactured, guaranteed unit from the Netherlands for less than half this amount, but not much less. These seem common enough in UK but were not available readily here in France. Importing from UK is difficult.

I have had the car back from the third garage for a few days. It was with them for 5 weeks. New turbo fitted. Hours and hours of work was expended with other garages being consulted and another mechanic borrowed for 3 hours to inspect the car in case anything had been overlooked. I was only billed for 10 hours, but then I was advised to buy a new turbo.

And now

I have not progressed beyond stage one.

The bills paid exceed €5500.

The sole OBD error is the same P2262 which can be cleared but which arises on first accelerating, together with the CEL light.

Please, please can any kind person give me advice, other than to set fire to the car, or whatever? I am practical, not a bad engineer and have a pretty fair idea about modern engines but am at the end of my tether.