[BBenedek]

Hey guys,

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).

Has anyone dealt with this exact combo before? Any input is appreciated!

[Lelleprinter]

When I serching for this P0427 errorcode it should be:
Front temperature sensor, catalytic converter. Signal too low

But if I check parts for motorcode D5244T (D5) in parts catalog this sensor seems not to be there.
I must ask you, is this S80 a modelyear 2006?
Or is it a modelyear 2007 but produced end of year 2006?
If so then these catalutic temperature sensors can be located in parts catalog for that model year.

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For the second error code p0299, please check Charge air hose from and to Charge air cooler for leakage.

Volvo DTC ECM-P029900
Make: Volvo
Code: ECM-P029900
Definition: Turbo/Super Charger Underboost

Description:
The Engine control module (ECM) regulates the turbo pressure using a turbo control valve.
The control module can detect small faults in boost pressure regulation over a longer period of time and larger faults in a shorter time.

The diagnostic trouble code (DTC) is stored if the control module detects that:
The actual turbo pressure is less (approx. 15 kPa for 10 seconds) than what the Engine control module (ECM) regulated (maximum regulation achieved).

The control module's test for the diagnostic trouble code (DTC) starts in the event of: Normal load (driving).
Boost pressure (approx. 30 kPa above atmospheric pressure).
Note! The control module can only detect the fault once the test has been started and the diagnostic trouble code (DTC) is stored when the conditions are met.

Cause:
-Damaged turbocharger (TC) control valve.
-Air leakage in the intake system.
-Damaged turbo charger (TC).
-Damaged relief valve.
-Hoses between the pressure servo for the boost pressure control (BPC) valve and the turbocharger (TC) control valve have come loose or are blocked or damaged.
-Sticking boost pressure control (BPC) valve.
-Damaged boost pressure control (BPC) valve pressure servo.