2001 Cadillac Deville system to lean

Tiny
SIKWITIT765
  • MEMBER
  • 2001 CADILLAC DEVILLE
  • V8
  • FWD
  • AUTOMATIC
  • 85,000 MILES
How to find and fix system to lean code P0171, P0174, banks 1, 2 system to lean
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Saturday, October 24th, 2009 AT 7:03 AM

4 Replies

Tiny
RASMATAZ
  • MEMBER
P0171/P0174

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)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)
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Saturday, October 24th, 2009 AT 7:16 AM
Tiny
SIKWITIT765
  • MEMBER
I just replaced the spark plugs could a faulty plug or not tourqing the right pounds of pressure for tightning the plugs can cause it to say system to lean banks 1, 2 P0171, P0174
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Saturday, October 24th, 2009 AT 7:27 AM
Tiny
RASMATAZ
  • MEMBER
That would cause an ignition misfire-why don't you check it. A lean condition is where the air/fuel mixture has more air than fuel during combustion.
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Saturday, October 24th, 2009 AT 9:17 AM
Tiny
FACTORYJACK
  • EXPERT
Check for a split boot between the intake manifold, and throttle body. It usually splits down on the lower portion of it, and is a very common cause of this symptom.
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Monday, October 26th, 2009 AT 11:00 PM

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