# *check engine light code p0172



## kate1yn (May 8, 2008)

hi i have a 1997 vw jetta trek. with a 2.0 4 cylinder. and my check engine light is on, the code is p0172 (bank 1 system running too rich) and a bunch of people told me that means it's my o2 sensors so i changed both of them and the light is still on.. and in my intake hose i keep getting all kinds of oil in there... ( is that suppose to be like that) what else should i do to turn fix this problem (is it my MAF) any suggestions?????


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## Pitsy (Oct 27, 2007)

*Re: *check engine light code p0172 (kate1yn)*

Get a new PCV valve (make sure it comes with the grommet) and a can of CRC MAF cleaner. Take off your intake hose and clean all the oil out of it. Wipe out your throttle body as much as you can. Remove the MAF housing from your airbox and clean it with the CRC. Pull off the old PCV valve and grommet (careful not to leave any of the grommet behind inside the valve cover) and pop in the new parts.
Put everything back the way you found it and you're done.
If you disconnect the battery cables for a while the CEL should turn off on its own.
Welcome to the Vortex!


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## kate1yn (May 8, 2008)

thanks i'll defiantely try that, but every website i go on to find a pcv valve it says they don't make 1 for my car it says they only make 1 for cars up to 1995 not 97 does it make a difference? can i use that?


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## Pitsy (Oct 27, 2007)

*Re: *check engine light code p0172 (kate1yn)*

I thought they were all the same, but I seem to recall...
My last car, a '96 Jetta, was OBD2. When I bought a replacement PCV valve for it, it didn't quite match and getting the hoses attatched was a bear.
My current car, a '95 Jetta, is OBD1. When I bought a replacement PCV valve for it, it was the same part number and it fit like a champ.
I know the intake boot is way different between OBD1 and OBD2, so I wouldn't be at all surprised if the PCV valve is different.
I will say, my old car ran fine with the (perhaps wrong) replacement PCV; it was just a PITA to install.
Let me research the part numbers for you and I'll post my findings.


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## Pitsy (Oct 27, 2007)

*Re: *check engine light code p0172 (kate1yn)*

Try this:
http://www.germanautoparts.com...158/3
Don't forget to grab a replacement grommet also. They usually break in the process of swapping.


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## FL 2.0L (Aug 1, 2002)

FYI after the fact:
Only the front O2 sensor affects fuel delivery. The rear sensor is strictly to monitor the functioning of the catalytic converter. It probably was unnecessary to change the rear sensor.
I'd clean the MAF, as above, and look for vac leaks in all hoses.


_Modified by FL 2.0L at 11:54 PM 5-13-2008_


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## Pitsy (Oct 27, 2007)

*Re: (FL 2.0L)*

X2 on the vacuum hoses. There's a bunch of them and a leak in any of them can make your car run poorly or not at all. Just go to the parts store and show them a section of your vacuum hose and get four or five feet of it. Good to keep in the car, along with something to cut it with. Keep it next to your duct tape.


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## kate1yn (May 8, 2008)

*thankyou*

thanks every 1 for all your help i fixed it, it was the freakin k&N filter i had in it, it was suckin up to much air into the intake hose causin the hose to get filled with oil. and run rich, as soon as i cleaned it and changed the filter back to the stock 1 the light turned off within a couple of hours...thanks


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## Pitsy (Oct 27, 2007)

*Re: thankyou (kate1yn)*

Well, I'm glad your car runs better now. I'm not sure if it was the K&N filter. After you cleaned everything, did you try the K&N in it?
I'm not trying to contradict what you've learned about your car, but I've never had a problem with K&N except when I used too much oil on it the first time.
Flowing more air through the intake shouldn't suck in more oil from the PCV. If anything, there will be less of a vacuum in the intake before the throttle plate. The bottom line is that if the PCV is in good shape, you shouldn't have more than a trickle of oil in the intake tube.
You can, however, easily over-oil a K&N. I did it once and the excess oil from that got blown onto the MAF sensor, making the motor run like doodoo.
Anyway, glad to hear it's running; surprised it was the K&N.


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