2001 Toyota Corolla 2001 T Corolla - P0171

2001 TOYOTA COROLLA
150,000 MILES • 4 CYL • 2WD • AUTOMATIC
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RKORD24
  • MEMBER
  • 1 POST
Hey Guys,

I have a 2001 Toyota Corolla, 150,000 miles. Check engine light is on. Had AutoZone run a diagnostic and it came up P0171 "system too lean". Took MAF sensor out, sprayed it thoroughly with CFC MAF Cleaner, disconnected the black battery cable for 10 minutes. Light was off upon starting, then popped back on a few miles down the road.

Anyone have any idea of what might be wrong? Or any other do it yourself'r checks I can perform or before dropping it off at the shop?

Thanks for your time.
Dec 17, 2007 at 2:01 PM
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RASMATAZ
  • ✓Experienced Mechanic
  • 75,992 POSTS
P0171 A lean fuel condition can be caused by:

Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (use a fuel pressure gauge to check fuel pressure at idle)

Dirty fuel injectors. (try cleaning the injectors)

Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

Leaky EGR valve. (Check operation of EGR valve)

Leaky PCV Valve or hose. (Check valve and hose connections)
Dec 17, 2007 at 2:57 PM
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