Dealing with a couple of annoying issues on my '06 S80 D5 (P3) and could use some advice.
First one is a persistent P0427 code (Cat temp sensor low input). Parts catalogs seem to be a complete mess when it comes to these exhaust sensors. Can anyone tell me exactly which sensor triggers this specific code and where it is located? I just want to make sure I buy and replace the correct part.
The second problem is driving me crazy. The car pulls great when cold, but if I do a highway run, stop at a rest area and restart it while it's still hot, it has absolutely no power. Feels exactly like limp mode—it revs freely but barely accelerates. Usually, there are zero codes for this power loss, but rarely, it throws a P0299 (Low boost) code. I strongly suspect the hot power loss and the occasional underboost code are connected.
I'm starting to suspect the fuel rail pressure sensor based on some digging, thinking maybe the crippled fueling is preventing the turbo from spooling.
(FYI: I recently had the entire swirl flap assembly replaced, so that should be perfectly fine now).
One quick side question while I'm here: the engine consumes a little bit of oil. Would you guys dare to switch from the standard 0W-30 to a slightly thicker 0W-40 or 5W-40 (a DPF-friendly C3 rated oil, of course) to help reduce consumption, or should I strictly stick to the factory spec?
Has anyone dealt with this exact combo before? Any input is appreciated!
