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CEL code: P0171

Featured Replies

My 2003 Subaru Outback H6 sedan with 156k miles just threw this code. The person at autozone said something about a MAF sensor but it appears our cars dont have this. Someone said something about cleaning the PCV valve or just buying a new one altogether. Any advice or recommendations? Planning on driving my car for the next week until I can fix it. 

Google the code. It is a fuel too lean condition. Lots of possible causes.

Will give you things to check.

 

O.

I'd want to inspect the fuel pump's cap and o-ring

 

could be anything that throws-off OR confuse the ECU about A:F ratio. MAP, front o2 sensor, vacuum leak.....

  • Author

Well my check engine light went off after driving in the snow for a little. Guess I'll have to see if it comes back on.

  • 2 months later...

I have the same code.. it keeps appearing.. I've taken off the MAF, cleaned with brake cleaner (non residue), and have put sea foam into the tank x 2 now, am currently checking vacuum hoses and looking for leaks there too.. no luck on finding those yet.. but the code continues to trigger.. I've read that it might be a bad EGR valve too.. but last night on my OBD DIag. and reading in another forum found that the Long term fuel trim and short term fuel trim readings (in a percentage) should not go higher than 14% when added together, I actually watched the long term steadily climb and the short term eventually as well. and I could see it was a pending code on the OBD Diag tool.. see the difference in the two screen captures.. 

Anybody have any other ideas?

 

bacc4e97-af2f-4c42-a98e-01a7d11d1c0f_zpsb8783ebf-b9fb-42ff-a02e-cade901b6c9e_zps

  • Author

Mine still comes on and goes off. I also haven't found out what is causing it. I have noticed that it will usually come on after some hard pulls; usually after driving for a couple miles. Then maybe less than 50 miles later it will go off again. Have you noticed any trends with your driving habits?

The check engine light triggers after a trip of more than 20 or so miles.. turn off engine for a short time, like filling up or shopping.. then back in and start up.. the engine is not all the way cooled off,

 

however after a long trip, no stops, turn off and the next day start up.. no light.. it's weird.. 

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