P0172 Solutions

Guest · Post by **Guest** » 17 Jan 2006, 16:10

So this is the code that I pulled my from 97 850 NA, this site has the possible solutions to the problem http://www.obd-codes.com/trouble_codes/ ... sensor.php

I know its not the MAF sensor because I replaced that, I checked the white vacuum lines and they looked fine. How can I check the fuel pressure at the fuel rail? What else shall I look out for? Thanks in advance.

Tsquared · Post by **Tsquared** » 17 Jan 2006, 19:40

Front O2 sensor - if you have never replaced either and the car has over 100K it is a good idea to replace both the front and rear sensor. Fairly easy job for the do-it-yoursef type.

Post by **matthew1** » 17 Jan 2006, 21:04

Check vacuum elbows too.

As for the code, I don't think you need to check fuel pressure because your mixture is too rich, which indicates too much fuel/not enough air.

Tsquared · Post by **Tsquared** » 09 Feb 2006, 18:22

I have had the P0172 code for about 2 months. I had recently replaced the O2 sensors so I was fairly sure that was not the problem. Tried a new MAF - no joy. Started looking at my vacuum elbows and found a few that were starting to deteriorate. Replaced all of them around the throttle body and intake area and followed them to the distant end and replace it as well. I still had the problem. I purchased an extra set of O2 sensors and tried that - still no joy.

I finally found a broken vacuum elbow on the front side of the engine that was the problem. It was located facing the front of the car about half way down the block near the timing cover.

I was able to use the rear O2 on another vehicle. I have a spare front O2 that has about 12 hunderd miles on it. Mew MAF on the car and good MAF with 125K miles sitting on the shelf. I now have 2 weeks to get the emissions test completed - cutting it too close for comfort.

T2

voltech1 · Post by **voltech1** » 12 Feb 2006, 04:08

You have a system too rich code lower limit. A vacuum leak will cause a(upper limit) lean condition and usually when a MAF dies it goes upper limit but not always. Check your ETC coolant temp sensor under the waterneck on top toward the front of the motor. If it looks scaley or coolant is coming out of the two wires replace it. The ECU will dump fuel if it thinks the car is even a little warm. If ECT is cruddy looking replace the thermostat at the same time.

subbaraa · Post by **subbaraa** » 02 Jul 2006, 10:58

Hi,
I saw some good replies here about trying to replace the vacuum elbows. The problem is I cannot find them on mine. I followed the instructions, I cannot find one near the thermostat either. Can someone please give more information on where to find it exactly?

I have replaced the MAF twice...
So I think I might have a leak too, but I just cannot find these elbows. The 99 S70 AWD turbo that I have, has a fly by wire throttle.

Thanks for your help in advance.

Post by **MadeInJapan** » 02 Jul 2006, 12:48

Maybe this will help.

subbaraa · Post by **subbaraa** » 02 Jul 2006, 13:02

hey
thanks for the reply. I found that on IPD as well, but I still cannot find those in my car. Am I supposed to remove the hose that connects the thermostat and the radiator, to be able to see this? Does it go into the intake manifold?

With regards to the elbow on the right (by the air intake), my car has an electronic throttle, and there is no white tube (as seen on the blown up pic above from the right elbow) that goes from the air intake to ....where is it supposed to connect to anyway?

Thank you very much for helping me out here...

vantassell · Post by **vantassell** » 29 Nov 2009, 17:35

I'm having a similar problem as the OP. I decided I'd add onto this thread rather than starting a whole new one.

I can find the vacuum elbow with a leak (on the passenger side of the manifold, under the power steering reservoir) but I can't actually get to the elbow. My elbow was disconnected entirely, there was a hose disappearing deep into the engine, and a hose connected to the manifold running perpendicular to the first hose, but no elbow.

I used a pry bar along the lines of the walk through at bay13 to get the clamp off of the hose connected to the manifold, but couldn't get the other hose to slid off of the 'plastic' hose that i've heard it's attached to. The hose looks like it's insulated with some spongy rubber, I can peel this back a bit, but I can't ever find a point that I can connect new hose to.

Am I doing this all wrong?

Post by **misha** » 29 Nov 2009, 17:51

Guest wrote:So this is the code that I pulled my from 97 850 NA, this site has the possible solutions to the problem http://www.obd-codes.com/trouble_codes/ ... sensor.php

I know its not the MAF sensor because I replaced that, I checked the white vacuum lines and they looked fine. How can I check the fuel pressure at the fuel rail? What else shall I look out for? Thanks in advance.

If your o2 sensors,Maf & vacuum lines are ok...then fuel pressure damper(regulator)can throw this po172 code when it's bad.Since you have '97 model you could have fuel pressure damper.It looks like this:

If it doesn't look like this then you have a fuel pressure regulator which is vacuum controlled.

Both of them can cause po172 code.