1995 Ford Mustang P0171 P0174 Lean

FORD MUSTANG
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SPONGE27
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  • 3 POSTS
I own a 1995 Mustang V6 3.8 liter and recently my check engine light came on. I borrowed a scanner and the codes that I got were P0171 and P0174. I have learned that these mean system too lean (bank 1) and system too lean (bank 2). What can cause this problem and how do I remedy it?
Feb 13, 2006 at 9:24 AM
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PEPPERMRJ
  • ✓Experienced Mechanic
  • 1,158 POSTS
code P0171 may mean that one or more of the following has happened:

The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters (K&N, etc.) can cause the MAF to become dirty if the filter is over-oiled
There could be a vacuum leak downstream of the MAF sensor.
Possible solutions include:

In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
Inspect all vacuum and PCV hoses, replace if necessary
Check for a dirty fuel filter and proper fuel pressure

Good luck and let us know,
Feb 15, 2006 at 12:44 PM
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Suggested Repair

Clean the MAF sensor with electronics or brake cleaner and let it dry fully before reinstalling. Inspect vacuum and PCV hoses for leaks and replace any that are damaged. Also check for a dirty fuel filter and verify proper fuel pressure. Avoid over-oiling aftermarket air filters, which can contaminate the MAF.

Conversation Summary

A 1995 Ford Mustang V6 3.8L owner reported a check engine light with codes P0171 and P0174, indicating both banks are running too lean. The expert said common causes include a dirty or faulty MAF sensor, often from an over-oiled air filter, a vacuum leak downstream of the MAF, or a fuel delivery problem. Recommended steps are cleaning the MAF, inspecting vacuum and PCV hoses, and checking the fuel filter and fuel pressure.

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