PO171 too lean

Wella Fella · Apr 4th, 2012, 18:54

Hi,

had the engine light on for a while now which shows PO171 fault code on 2Ltr T4. I've searched this forum for a fix but cannot seem to work this one out. I've done the following:

1) Searched every hose and pipe and cannot find any leaks - both physically removed and examined and sprayed joints with carb cleaner looking for dip in engine tone.
2) Replaced fuel filter - made no difference
3) Replaced post cat o2 sensor - made no difference
4) Cleaned out the idle control valve as it was rough at idle when cold - wasn't that dirty and made no difference.
5) Shouted and swore at the car - made no difference but I felt slightly better after a good rant. But the light is still on.

The car isn't running badly except as mentioned when it's cold when it judders and splutters but with some extra revs it shuts the hell up and gets on with it. No loss of power through normal driving.

I replaced the MAF about 2 years ago.

Please help with any suggestions !!! I'll try anything.

mitchyboy01 · Apr 4th, 2012, 19:10

Is that hawkinge near Folkestone? I'm only down the road. Have you tried disconnecting the MAF from cold and seeing if it runs better? I can get your codes read Again if need be.

960kg · Apr 4th, 2012, 20:09

What is your mileage ?

Sounds like weak fuel pump pressure, low.

Or if you fitted a copy MAF it could be that ?

Keith
I`m in Hythe!

Wella Fella · Apr 4th, 2012, 21:49

Yes Hawkinge near Folkestone and Hythe !!!

I've run it with the MAF disconnected and the DSA light comes on. A short while ago, the DSA light came on during normal driving with everything connected and again ran fine, but this went off. At this point, having done that with the MAF disconnected, I was convinced it was the MAF but the light went off in a few journeys and hasn't come on again since. This was before Christmas.

Volvo wanted over £350 for a new MAF back when that went so I laughed at the guy and went and bought a copy part from either AJAY's or Euro Part on Park Farm estate.

In essence though disonnecting the MAF makes little difference to the way it runs (apart from DSA light).

I'm so frustrated with it!!!

Someone said it could be the pre CAT O2 sensor??? Could that be the cause?

Wella Fella · Apr 4th, 2012, 21:49

Forgot to say - mileage is nearing the big 100k.

mitchyboy01 · Apr 4th, 2012, 22:06

Could be pre cat lambda. I have a spare lambda. Not sure if it's pre or post cat though?

Wella Fella · Aug 9th, 2012, 21:56

OK, so all this time later, having had no joy finding air leaks or anything else, and the car running just fine with only very intermittent and barely noticable 'chugging' when cold, I finally bit the bullet and took it Volvo for their magic all knowing computer to reveal all. They told me PO171. Brilliant. No further forward now (but I managed to get them to do it for free!!!) Their parting shot was that this code is an absolute pain and it often takes a good number of hours to resolve it, but then they would say that wouldn't they!!!

They've suggested it could the the carbon deposits inside the engine causing the fault code. That doesn't really figure in my head as to how this could cause the lean reading. Any ideas???

Cars got 103k on the clock. Barely scraped through the emissions test last MOT and I wondering if that terraclean would be worth a shot?? I don't want to pay out for more stuff just to throw money away if there's no chance it will resolve the issue.

T4Rick · Aug 9th, 2012, 22:02

Ive got a 2.0t maf if you need one.Ive got my book of codes out and it says system to lean bank 1

960kg · Aug 10th, 2012, 11:25

Quote:

Originally Posted by Wella Fella

OK, so all this time later, having had no joy finding air leaks or anything else, and the car running just fine with only very intermittent and barely noticable 'chugging' when cold, I finally bit the bullet and took it Volvo for their magic all knowing computer to reveal all. They told me PO171. Brilliant. No further forward now (but I managed to get them to do it for free!!!) Their parting shot was that this code is an absolute pain and it often takes a good number of hours to resolve it, but then they would say that wouldn't they!!!

They've suggested it could the the carbon deposits inside the engine causing the fault code. That doesn't really figure in my head as to how this could cause the lean reading. Any ideas???

Cars got 103k on the clock. Barely scraped through the emissions test last MOT and I wondering if that terraclean would be worth a shot?? I don't want to pay out for more stuff just to throw money away if there's no chance it will resolve the issue.

Just trying to help ,if you go to Volvo again ,i use Ashford for my parts but go to Canterbury if i book the car in. They have more elderly really experienced mechanics there and are superb. Easy to get to via Stone Street, have a Google on the maps

Wella Fella · Aug 18th, 2012, 15:51

Thanks all for your help. Still not established what the problem is but will update once I do.

Apr 4th, 2012, 18:54	#1
Wella Fella Junior Member Last Online: Feb 8th, 2023 23:13 Join Date: May 2010 Location: Hawkinge	PO171 too lean Hi, had the engine light on for a while now which shows PO171 fault code on 2Ltr T4. I've searched this forum for a fix but cannot seem to work this one out. I've done the following: 1) Searched every hose and pipe and cannot find any leaks - both physically removed and examined and sprayed joints with carb cleaner looking for dip in engine tone. 2) Replaced fuel filter - made no difference 3) Replaced post cat o2 sensor - made no difference 4) Cleaned out the idle control valve as it was rough at idle when cold - wasn't that dirty and made no difference. 5) Shouted and swore at the car - made no difference but I felt slightly better after a good rant. But the light is still on. The car isn't running badly except as mentioned when it's cold when it judders and splutters but with some extra revs it shuts the hell up and gets on with it. No loss of power through normal driving. I replaced the MAF about 2 years ago. Please help with any suggestions !!! I'll try anything.

Apr 4th, 2012, 20:09	#3
960kg Premier Member Last Online: Dec 28th, 2022 12:25 Join Date: Jun 2009 Location: Mercville	What is your mileage ? Sounds like weak fuel pump pressure, low. Or if you fitted a copy MAF it could be that ? Keith I`m in Hythe! __________________ Mercedes C320CDI Sport Estate 3 litre V6 7 Gear Auto Remap 290bhp 628Nm torque @ 1600revs 45.1mpg

Aug 9th, 2012, 22:02	#8
T4Rick Premier Member Last Online: Oct 11th, 2012 08:49 Join Date: Jun 2010 Location: manchester	Ive got a 2.0t maf if you need one.Ive got my book of codes out and it says system to lean bank 1 __________________ I said a 10 second car not a 10 minute car Chipped and rolling roaded at 221.9 hp at std boost Horns relocated for better air flow with a Horn from a Vag,Coil overs fitted

Apr 4th, 2012, 19:10	#2
mitchyboy01 Premier Member Last Online: Oct 25th, 2020 06:40 Join Date: Jun 2011 Location: Dover	Is that hawkinge near Folkestone? I'm only down the road. Have you tried disconnecting the MAF from cold and seeing if it runs better? I can get your codes read Again if need be.

Apr 4th, 2012, 21:49	#4
Wella Fella Junior Member Last Online: Feb 8th, 2023 23:13 Join Date: May 2010 Location: Hawkinge	Yes Hawkinge near Folkestone and Hythe !!! I've run it with the MAF disconnected and the DSA light comes on. A short while ago, the DSA light came on during normal driving with everything connected and again ran fine, but this went off. At this point, having done that with the MAF disconnected, I was convinced it was the MAF but the light went off in a few journeys and hasn't come on again since. This was before Christmas. Volvo wanted over £350 for a new MAF back when that went so I laughed at the guy and went and bought a copy part from either AJAY's or Euro Part on Park Farm estate. In essence though disonnecting the MAF makes little difference to the way it runs (apart from DSA light). I'm so frustrated with it!!! Someone said it could be the pre CAT O2 sensor??? Could that be the cause?

Apr 4th, 2012, 22:06	#6
mitchyboy01 Premier Member Last Online: Oct 25th, 2020 06:40 Join Date: Jun 2011 Location: Dover	Could be pre cat lambda. I have a spare lambda. Not sure if it's pre or post cat though?

Aug 9th, 2012, 21:56	#7
Wella Fella Junior Member Last Online: Feb 8th, 2023 23:13 Join Date: May 2010 Location: Hawkinge	OK, so all this time later, having had no joy finding air leaks or anything else, and the car running just fine with only very intermittent and barely noticable 'chugging' when cold, I finally bit the bullet and took it Volvo for their magic all knowing computer to reveal all. They told me PO171. Brilliant. No further forward now (but I managed to get them to do it for free!!!) Their parting shot was that this code is an absolute pain and it often takes a good number of hours to resolve it, but then they would say that wouldn't they!!! They've suggested it could the the carbon deposits inside the engine causing the fault code. That doesn't really figure in my head as to how this could cause the lean reading. Any ideas??? Cars got 103k on the clock. Barely scraped through the emissions test last MOT and I wondering if that terraclean would be worth a shot?? I don't want to pay out for more stuff just to throw money away if there's no chance it will resolve the issue.

Aug 18th, 2012, 15:51	#10
Wella Fella Junior Member Last Online: Feb 8th, 2023 23:13 Join Date: May 2010 Location: Hawkinge	Thanks all for your help. Still not established what the problem is but will update once I do.

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