1997 850 NA - Cannot clear P0172

dejongmc · Post by **dejongmc** » 11 Aug 2014, 08:59

I have this code for a while now and it will not go away. Here a list of things I did so far:

- Replaced all vacuum lines incl. canister under intake manifold
- Replaced spark plugs and wires (were due anyway)
- Replaced MAF sensor
- Sprayed Throttle Body cleaner on all vacuum connections while can is idling, but no luck.

I know that the O2 sensors are past due but from what I gathered a faulty O2 sensor doesn't cause this issue. But maybe someone has a different experience? Should I replace at least the front O2 sensor?

My lost resort at this point is to see if I can find a smoke machine to blow the smoke in the PCV system to see if I can find another leak.

Anybody else have an idea what to do?

JeffHicks · Post by **JeffHicks** » 11 Aug 2014, 09:35

Are you clearing the code with a scanner, or just waiting for it to go away? If you're just waiting for it to go away on its own, that's going to take quite awhile.

If you don't have a scanner that can clear the codes, you can clear them by disconnecting the negative battery cable and leaving it disconnected for half-hour. Just know that you'll have to re-code your radio.

dejongmc · Post by **dejongmc** » 11 Aug 2014, 09:41

I have a OBD scanner to read the codes and to clear the codes.
I cleared it a few times but P0172 keeps coming back.

Post by **rmmagow** » 11 Aug 2014, 10:09

Is it a Bosch MAF sensor? If yes, check the wiring closely. you may have a connector problem.

dejongmc · Post by **dejongmc** » 11 Aug 2014, 10:48

Yes, it is a brand new Bosch MAF sensor.
I cleaned the connectors.

I also replaced the distributor cap and rotor.

Post by **rmmagow** » 11 Aug 2014, 11:22

Sometimes the connector gets sort of worn out a bit and needs to be attached via like a velcro strip to the housing to help the connection stay in place. There's an article/pictures here that better describe what I am talking about. on my 98 V70 I had to do this and the p0172 then went away. My v70 is a turbo though but I think the MAF thing is a common to all issue.
Is your fuel pressure too high? Pressure regulator working correctly? I'd seriously consider the O2 sensor at this point too.

dejongmc · Post by **dejongmc** » 12 Aug 2014, 10:25

Does anybody know where you can rent one of those smoke machines to find vacuum leaks, here in Houston?