Hi all
Just wanted to share what I have been through with my XC90 in a hope that it will help anyone in need.

I recently bought my first Volvo, a 2010 XC90 D5 with 117kms. One week after buying it I started having trouble with the car going into limp mode every time I went up a hill, not a big problem except I live in the hills.
The symptoms were weird, it was as if there was a camera mounted on the front of the car and every time it saw a hill in front it would suddenly lose power. The car would be doing 3500rpm flat out at 40km/h.
I have a diagnostic scanner so I pulled the following codes:
ECM-1517 Turbo control. Pressure too high
ECM-1540 Turbo control. Pressure too high
ECM-135F Mass Air Flow (MAF) sensor
ECM-1507 Turbo Control. Too low pressure

TCM-0A31 Control module communication. Signal missing from Engine Control Module (ECM)

After discussing it with the dealer who I bought the car from, they arranged for me to take it to a total of four different mechanics.
The first was useless and wanted to replace the turbo at s guess.
The second read codes only.
The third (Volvo dealership) diagnosed a cracked inlet manifold.
The fourth confirmed the cracked inlet manifold by inducing pressurised smoke (fogging) which spewed out of the cracks.
Initially they thought it was the two rubber couplings on the turbo pipe at the rear of the engine but these checked out fine. I had explained to three of the mechanics that I had noticed muck build up around the diesel injectors which the last two agreed was not normal.
The last mechanic got the job because he was cheaper (50%) than the dealership. It cost around $1700 to do, it was also recommended by mechanic #2 to replace the swirl vanes and actuator arm for an extra $500 but mechanic #4 advised that it was not necessary. I did pay an extra $500 for a full service with oil, air and fuel filter changes; at least I now have a benchmark for the car and it's wellbeing.
Now the car runs like it should.
Hope this helps someone else 👍