[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 catalytic temperature sensors can be located in parts catalog for that 2007 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.

[BBenedek]

Sorry for the delayed reply, I've been completely swamped lately!

To answer your question, my car was manufactured in November 2006 (so it definitely uses the MY2007 parts catalog).

As for the P0299 code, I've put that on hold for now because it hasn't popped up in a long time. Just to be sure, I went ahead and tightened all the turbo hose clamps a while ago, so there is a good chance that actually solved the issue.

Now, regarding the P0427 code. I was completely misled: the sensor screwed into the DPF (accessible from underneath) was a cobbled-together, soldered Fiat/Alfa Romeo part, which naturally made me highly suspicious of it. To add to that, when I unplugged it, it immediately flipped the code to "high input", so I focused all my attention down there. Based on what you said, I should have been looking at the top one (catalyst) this whole time!

My question is: should I start by checking the wiring first (or taking it to a professional), or do you recommend just replacing the top sensor right away? If so, what exact part should I buy?

On a separate note, an oil change is coming up soon. I'm currently running Motul 8100 Eco-nergy 0W-30. Oil consumption is minimal, but the hydraulic lifters are slightly noisy/clicking. I know it's not unusual at 284,000 km, but I'm wondering if a different oil choice could quiet them down a bit.

I'm considering three options:
A) Stick with the current Motul 0W-30?
B) Switch to the factory-recommended Castrol 0W-30 (A5/B5)?
C) Would trying a 0W-40 oil be worth a shot? I know it has higher viscosity at operating temperature — which is precisely why I'm considering it for the slight oil burn and the lifter noise — or are the strict 0W-30 tolerances non-negotiable on this D5 engine?

Thanks again for the help and the detailed info, it really pointed me in the right direction!

[Lelleprinter]

Now, regarding the P0427 code.
I was completely misled: the sensor screwed into the DPF (accessible from underneath) was a cobbled-together, soldered Fiat/Alfa Romeo part, which naturally made me highly suspicious of it.
To add to that, when I unplugged it, it immediately flipped the code to "high input", so I focused all my attention down there. Based on what you said, I should have been looking at the top one (catalyst) this whole time!

My question is: should I start by checking the wiring first (or taking it to a professional), or do you recommend just replacing the top sensor right away?
If so, what exact part should I buy?

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Due to the price for this temperature sensor I should go for just replace that sensor directly.
My assumption are that you have motorcode D5244T4 with catalytic converter Emission code 4.

Please check parts list below.
It should be item 18 and there are two different parts number depending on chassi number.

Spareparts S80 2007.png (289.56 KiB) Visad 18 gånger

[Lelleprinter]

On a separate note, an oil change is coming up soon.
I'm currently running Motul 8100 Eco-nergy 0W-30.
Oil consumption is minimal, but the hydraulic lifters are slightly noisy/clicking.
I know it's not unusual at 284,000 km, but I'm wondering if a different oil choice could quiet them down a bit.

I'm considering three options:
A) Stick with the current Motul 0W-30?
B) Switch to the factory-recommended Castrol 0W-30 (A5/B5)?
C) Would trying a 0W-40 oil be worth a shot?
I know it has higher viscosity at operating temperature — which is precisely why I'm considering it for the slight oil burn and the lifter noise — or are the strict 0W-30 tolerances non-negotiable on this D5 engine?

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I will translate this question to Swedish and see if some with better knowledge will respond and advice.
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Vad säger ni om nedan fråga om oljebyte till annan kvalitet vill göra att de hydraliska ventillyftarna blir tystare?
Ni kan svara på svenska om ni vill så översätter jag.
-

På tal om annat, ett oljebyte är på gång snart.
Jag kör för närvarande Motul 8100 Eco-nergy 0W-30.
Oljeförbrukningen är minimal, men de hydrauliska lyftarna är lite bullriga/klickande.
Jag vet att det inte är ovanligt vid 284 000 km, men jag undrar om ett annat oljeval skulle kunna tysta ner dem lite.

Jag överväger tre alternativ:
A) Hålla fast vid den nuvarande Motul 0W-30?
B) Byta till den fabriksrekommenderade Castrol 0W-30 (A5/B5)?
C) Skulle det vara värt ett försök att prova en 0W-40-olja?

Jag vet att den har högre viskositet vid driftstemperatur – vilket är just därför jag överväger den på grund av den lätta oljeförbränningen och lyftarljudet – eller är de strikta 0W-30-toleranserna inte förhandlingsbara på denna D5-motor?