New here, but had my V40 for 8 years now. I think I’ve change almost most things on this car now 
Within the last year:
New:
Turbo
Catalytic convertor
DPF
All 4 injectors
EGR
All new wheel bearings, both axels, steering rack, steering arms, calipers, pads, brake disk’s, guide pins, brake fluid, brake hoses and bolt – all over
Inlet manifold fully disassembled, cleaned and flushed, new rubber seals and all inlet valves are blasted and cleaned with some fanzy stuff that cleans out all soot and build-up.
Intercooler flushed and all hoses + fixtures are cleaner, replaced or checked
MAF, inlet pressure sensor and temperature sensor are cleaner too
Original volvo 16″ XC rims with new tires
Diff sensor – tried 4 different from different dealers – none worked – all gave crazy erratic values in read-outs. Found a used one from a wreck from same year – seems to work… but still fly around with randoms values sometimes.
Never had an engine code/fault.
But the regen each 100-120 km, and I’ve cleaned everything – manifold, exhaust, inlet… you name it.
And the fuel economy is ok sometimes, but often it makes no sense, since the value is high, even though the road conditions are pretty good, and other times it shows around 18km/L, even though it is slightly up hill…. which makes me wonder big time.
It pulls well, and after I cleaned the TCV – Turbo Control Valve ( included the little airfilter in it) acceleration is much smoother again.
Looking into NTC sensors, since I’ve had both out and blew on them with a hot air gun, to see if the resistance was the same on each sensor – they are after all the same sensor on both the catalytic convertor and DPF – just different wire lenght. At higher temperatur the NTC in the catalytic converter, did start to show different values than the one in the DPF, but since I do not know which one is good or not – I have no reference, and therefore feel the need to change both – even though no faults are stored.
Any other sensor I need to look at or clean? Inlet pressure, fuel pressure, MAF, lambda probe(does it even have one? ) ??
Further – should the TCV valve close one way and open the other? I mean… how can I truly check it?
As said – the car pulls like a train ( last owner gave it 156hp and 30Nm and confirmed on dyno) and I’ve never seen a fault with either tester ( 3 different, one being Vida ) or in the dashboard – and I mostly drive beyond 20-100km each trip – mostly the long ones and prewarmed with engine heater ( eberspacher).
Car has regular service, Koni FSD dampers, new springs all bushings and joints are changed, full 4 wheel alignment
Main issue is:
Mostly low fuel economy all year and conditions
Seems to have too much soot in exhaust
Low millage between regen – 100-120km
Sometimes shaking when acceleration – sometimes not – but mostly shaking from engine – even at idle you can see a bottle of water on the passenger seat have ripples on the surface.
Hope someone has an idea
Even with no faults, I have been advised to change both EGT (NTC) sensors – since they should have a big effect on how the ECU controls fuel injections. Could that be true?
Thanks for any advice from here