P0172 Solutions

Post by **jtp** » 29 Nov 2009, 19:26

vantassell, I've had your problem for a while. The elbow your struggling with connects to a long tube, which is insulated as you saw, that runs the length of your intake manifold and then connects to your intake air duct (the large plastic tube between your MAF and throttle body) at the rear of the large elbow immediately upstream your throttle body.

I just had the intake mani off my car yesterday and only one line should be going into its passenger side. There should be the single elbow that fails on everybody and a single line going into it. It is very hard to get to but I was able to fix it with two needle nose pliers.

That said, after I fixed it I've still had the code and yesterday I found some cracks in the long insulated tube described above. The only way to fix these was to take the intake mani. off which is written up on several sites as part of the PCV system replacement.

vantassell · Post by **vantassell** » 29 Nov 2009, 20:15

jtp wrote:vantassell, I've had your problem for a while. The elbow your struggling with connects to a long tube, which is insulated as you saw, that runs the length of your intake manifold and then connects to your intake air duct (the large plastic tube between your MAF and throttle body) at the rear of the large elbow immediately upstream your throttle body.

I just had the intake mani off my car yesterday and only one line should be going into its passenger side. There should be the single elbow that fails on everybody and a single line going into it. It is very hard to get to but I was able to fix it with two needle nose pliers.

That said, after I fixed it I've still had the code and yesterday I found some cracks in the long insulated tube described above. The only way to fix these was to take the intake mani. off which is written up on several sites as part of the PCV system replacement.

Yikes, sounds like this just got a lot more complicated. I think I need to replace/clean out my current PCV system, so hopefully i'll get two birds with one stone.

At least now I now where the other end of the insulated tube connects

thanks, very helpful

Post by **jtp** » 30 Nov 2009, 05:20

vantassell wrote:
Yikes, sounds like this just got a lot more complicated. I think I need to replace/clean out my current PCV system, so hopefully i'll get two birds with one stone.

My thinking exactly, that's why I spent the weekend doing my PCV system and finding vac. problems in the process.

That said, if you're not set on doing the whole PCV job it's probably likely that just the elbow is your problem. It fails on everybody and my case is the first I've read of with cracks in the PCV system piping. I pulled on those pipes often and hard when I fixed the elbow, maybe that caused the cracks.

It can't hurt to fix the elbow and then see what happens with the code. Mine went from on all the time to on for a while, off for a shorter while.

I'd put myself at "somewhat experienced novice," 2 1/2 wrenches in my Haynes book, and that PCV job was the craziest thing I've gotten myself into in a long time.

Post by **schigara** » 30 Nov 2009, 09:11

Wouldn't leaky injectors cause the same rich condition?

Post by **matthew1** » 30 Nov 2009, 13:46

I popped that elbow off about 6 months ago during a high speed interstate highway blast. Took a long time to find the cause. Got a PO172, dropped to 22mpg highway, and like jtp had to fix it with long (long!) needlenose pliers I bought especially for it. It's a b!#ch.

A week later it happened again and I reversed the elbow (it's not symmetrical) and haven't had the problem since.

Don't know if this will help, but here it is.

vantassell · Post by **vantassell** » 09 Mar 2010, 22:00

Just an update in case anyone searches this thread out later. My P0172 code was cleared after fixing the vacuum elbow mentioned.

I had to get some ridiculously long pliers at harbor freight to get the job done. I think they were 16" or so.

Thankyou SOOOO much for the help. Probably saved me two o2 sensors and lots of mechanic time.

William Daly · Post by **William Daly** » 26 Sep 2010, 12:20

replaced broken elbow ran new vacuum line totoboth sids ontop of fire wall code gone to hard to get elbow on old line cost $20 bucks thanks

William Daly · Post by **William Daly** » 27 Sep 2010, 19:54

fixer code po172 one day now have po243 wastegate silinoid could wastegate be stuck can ifree it can ispray it with s.omething or will i just replace the control selinoid can it be adjusted . dono what it (selinoid valve on wastegate) looks like will check vac. lines elbows ,hoses any ideas....thanks

washdup · Post by **washdup** » 17 Apr 2012, 05:28

voltech1 wrote: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.

I'm resurrecting this thread because my car just lit up a P0172 code. It also seems to be idling slightly higher than normal, around 9750 or 1000. I recently swapped turbochargers, but had no code for three weeks. The reason why I highlighted the post above is because I've been battling a pesky recurrent leak from the aft side of the upper radiator hose, and I think I've got it cured now, but not before it managed to drip all over everything below it. There is indeed some built-up coolant residue crud on the temp sensor, but the temperature reading it's giving is normal (center of Temp gauge). If the temp is normal, why would sensor crud cause a rich condition? Would it be ok to spray it with WD-40 to clean it off?

Post by **erikv11** » 17 Apr 2012, 06:59

Sounds more like a vacuum leak is causing the p0172.

The crud doesn't cause the sensor to go bad, the reason to look for crud is because if it is leaking coolant out through the wires then it is already bad. So scale due to getting dripped on is not going to be a problem, just clean it off. To clean it off WD-40 is ok but I would probably use hot water and an old toothbrush, try to rise off all the spilled coolant leftover from the hose problems.

P0172 Solutions

Re: P0172 Solutions