It's P0171 & P0174 not Pc 171 & Pc174 ! The engine computer has detected a lean condition ! That mean's it's not getting enough fuel or has a vacuum leak , bad O2 sensor ! fuel pump getting weak . fuel pressure regulator weak !
P0171 - System to Lean (Bank 1)
The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. Refer to Section 1 , Powertrain Control Software, Fuel Trim for more information.
Air Measurement System
- MAF sensor (contaminated, damaged, malfunctioning, etc.)
Fuel System
- Fuel pressure regulator (leaking, malfunctioning, etc.).
- Fuel filter plugged, dirty.
- Fuel pump (weak, check valve leaking, etc.).
- Leaking/contaminated fuel injectors.
- Low fuel pressure or running out of fuel.
- EVAP canister purge valve leaking (when canister is "clean").
- Fuel supply line restricted.
- Fuel rail pressure sensor (incorrect reading).
Air Induction System
- Air leaks after the MAF.
- Vacuum Leaks.
- PCV system (leak, valve stuck open, etc.)
- Improperly seated engine oil dipstick.
Exhaust System
- Exhaust leaks before or near the HO2Ss (exhaust manifold gasket, mating gaskets, etc.).
EGR System
- EGR valve tube/gasket leak
- EVR solenoid vacuum leak
Secondary Air Injection
- Damaged/malfunctioning secondary air injection system (mechanically stuck valve).
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P0174 - System to Lean (Bank 2)
The Adaptive Fuel Strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. Refer to Section 1 , Powertrain Control Software, Fuel Trim for more information.
See Possible Causes for DTC P0171.
See Diagnostic Aides for DTC P0171
View Freeze Frame Data to determine operating conditions when DTC was set. Observe LONGFT1 and 2 PID(s). Refer to Section 2 , Adaptive Fuel DTCs Diagnostic Techniques for more information.
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