2008 XC90 3.2L with codes P0171 and P0174 - Help

Hey guys,

I have a 2008 XC90 3.2 AWD with 75,000 KMS that I got recently.

Checking with OBD FUSION, I got the codes:

P0171 and P0174 System Too Lean

P0507 Idle Air Control RPM Higher than expected.

The car feels and drives normal but I want to fix these before it gets worse.

Searching on the web for these codes P0171 and P0174 its look like maybe the problem is the PCV but I don’t find any info, pics or DIY fix for this issue on a 3.2L engine

Have any of you with 3.2L engine has experienced these same codes?

I going to check if I have a vacuum hose leak but can you advise were I need specially to look

Thank you for your time and help

Isaac

[rj240]

I would recommend going to a dealer or Volvo specialist, and having the car scanned with VIDA. You will get a lot more information regarding the codes and it should guide you better toward finding out what's actually wrong with your car...

[Turbo_Boss]

Hello Rj240

The thing is if I go to the dealer it will cost me a fortune.:crying: I usually can Do my own repairs, so that why I am asking for this in order to save a lot of money.

THX,

Isaac

[C70-T5]

Hello Rj240

The thing is if I go to the dealer it will cost me a fortune.:crying: I usually can Do my own repairs, so that why I am asking for this in order to save a lot of money.

Well, Isaac, try to find somebody who have a "Vida Dice" to scan your XC90... ...May be a CVQ's member near you?

[rj240]

I didn't say to go and have it repaired at a dealer or Volvo specialist, but rather to have it scanned by one of them using the Volvo scan tool.

By having more detail and more information, it should save you money by pointing you down the right path, rather than changing parts unnecessarily and/or wasting time...

Often experience can save you a lot of time and money... Your local dealer/Volvo specialist does this kind of thing all day long, every day...

[Gunvolvo]

I didn't say to go and have it repaired at a dealer or Volvo specialist, but rather to have it scanned by one of them using the Volvo scan tool.

By having more detail and more information, it should save you money by pointing you down the right path, rather than changing parts unnecessarily and/or wasting time...

Often experience can save you a lot of time and money... Your local dealer/Volvo specialist does this kind of thing all day long, every day...

big +1

[Turbo_Boss]

I didn't say to go and have it repaired at a dealer or Volvo specialist, but rather to have it scanned by one of them using the Volvo scan tool.

By having more detail and more information, it should save you money by pointing you down the right path, rather than changing parts unnecessarily and/or wasting time...

Often experience can save you a lot of time and money... Your local dealer/Volvo specialist does this kind of thing all day long, every day...

Hey rj240,

Sorry if my reply sound no polite. English is my second lenguage.

Here in my country I have not found a mechanic that can diagnostic Volvo cars. Volvo is not a popular brand car in my country (figured why ) There are plenty mechanics that work on BMW and VW/Audi but when you take them a Volvo, they scratch there head.

So in many cases, I do a search on the net for the problems in order to do my own fixes. If is a PITA to do the fix, I take the car to a mechanic and guide him how to do the job.

Belived or not, I also have a Skoda Octavia 1.8T and took the car to make a oil change and they was scraching there head how to remove the metal plate under the engine.

So I always have to be like a police checking over the mechanic shulder what they are doing.

Thank you if there was any misundertanding in my last reply

Isaac

[Turbo_Boss]

Hey Guys,

After several web searches, I found that these two codes are related to the PCV OIL TRAP – VALVE COVER. Since the membrane/diaphragm is damage, it allow air to enter in the system that the MAF is not metering and that why it trow System Too Lean codes.

This is causing a small misfire and I am pretty sure is consuming more fuel.

So today I was checking the black housing on top of cylinder head and the first thing I notice is that is all covered in oil.

Also notice a hissing noise that is coming from the engine oil cap. I removed the oil cap and put my hand over the hole and there is a "noticeable" suction.

I am thinking in ordering:

PCV OIL TRAP – VALVE COVER Part No. 31319642
VALVE COVER GASKET Part No. 30731243


So today I have more time to check the valve cover Oil Trap and in the name of the science, research and investigation :-) I decide to remove the plastic cap on top of the diaphragm housing.

I know other brands like VW and BMW sell the membrane/diaphragm alone so I was expecting to see if I can replace it and save some $$$

I went to a place where they sell OEM and aftermarket parts for BMW. They were very similar but none of them fit or was the same.

On the Volvo membrane/diaphragm there is a part No. CF W 3A MB66-24

Doing a search on the net I don’t find anything under that part No. or something similar.

Anybody knows where can I get this part? If not, I will have to buy the complete valve cover oil trap :-(

THX,

Isaac

[Turbo_Boss]

Hey Guys.

So yesterday, I change the PCV OIL TRAP – VALVE COVER Part No. 31319642 on my 3.2L and cleared/reset the P0171 and P0174 System Too Lean codes and now the engine is smooth and not misfires.

So today I was driving and my check engine light come on and these are the codes I get:
P0172 and P0175 System too Rich.

Any advice what to check? Or what other test to make with the OBD Scanner?

THX,

Isaac

Here is the screen shot of the OBD Codes and also the Term Fuel % on idle on Bank 1 & 2

[DGM]

The "adaptives" are still set on the lean side (LTFT Pos). Now that the PCV is fixed (less air & normal air draw) the system measures a rich condition (STFT Neg). The scanner shows pending codes and the issue could disappear in the next few days (LTFT should decrease and STFT would be closer to Zero).

If not the following should be verify;

- An obstruction in the air path of the PCV system (ex: stuck or inoperative valve)
- A dirty/ clog air filter
- A dirty /defective MAF
- Stuck open thermostat / System not reaching closed loop
- Too much fuel pressure
- Dirty/ leaky fuel injectors
- An exhaust leak before the O2 sensors

My 5 cents.

[Turbo_Boss]

The "adaptives" are still set on the lean side (LTFT Pos). Now that the PCV is fixed (less air & normal air draw) the system measures a rich condition (STFT Neg). The scanner shows pending codes and the issue could disappear in the next few days (LTFT should decrease and STFT would be closer to Zero).

If not the following should be verify;

- An obstruction in the air path of the PCV system (ex: stuck or inoperative valve)
- A dirty/ clog air filter
- A dirty /defective MAF
- Stuck open thermostat / System not reaching closed loop
- Too much fuel pressure
- Dirty/ leaky fuel injectors
- An exhaust leak before the O2 sensors

My 5 cents.

Hey DGM,

Thank you so much for your reply.

I undertand that maybe the computer is adapting to this.

Yestarday night I reset the codes and today I have not seen the engine check light coming on :bowdown:

Let see whats going on this week and I will keep you updated.

THX,

Isaac

[DGM]

Good,

Having LTFT opposite to STFT is normal after a repair (ex: an air leak). The fuel mapping of the ECM for various load & rpm must be readapted to its new environment.

Some erase completely the ECM memory (wipe out) to force a relearn from scratch. It can take up to 500km to re-establish a complete map depending of car/model/years. Your fuel economy will improve.

[Turbo_Boss]

Good,

Having LTFT opposite to STFT is normal after a repair (ex: an air leak). The fuel mapping of the ECM for various load & rpm must be readapted to its new environment.

Some erase completely the ECM memory (wipe out) to force a relearn from scratch. It can take up to 500km to re-establish a complete map depending of car/model/years. Your fuel economy will improve.

Hey DGM,

When you say to erase the ECM memory, you mean to disconect the battery for 10 Minutes? Or can I remove just only the ECM Fuse? :scratch:

THX,

Isaac

[DGM]

In an ideal world Vida-Dice is used to reset "adaptives".

Personally I use the following procedure: turn-off radio, climate system, lights. Open tailgate, wait 5 minutes for systems to fall asleep. Disconnect in sequence negative and positive terminals at the battery. With the terminals disconnected in your hands touch the leads together for more than 5 seconds. This action will dissipate the residual energy left on the network. Then reconnect terminals, positive first. Close the tailgate, lock-unlock 3 times to reinitialize the alarm/sunroof/lock functions. Readjust the clock and input radio code if applicable. Start engine and drive normally. The engine may run a little bit rough and transmission may shift harder for a while until new parameters will be learned.

This will bring the ECM back to Volvo baseline. From there new "adaptives" will be stored to fine tune ECM to your vehicle.

You will find more information on this reset procedure on various Volvo Forums.