P0172 - System Too Rich (Bank 1)

Powertrain DTC Charts and Descriptions 4-35

Diagnostic Trouble Code (DTC) Charts and Descriptions

P0172 - System Too Rich (Bank 1) (Continued)

• EVAP purge valve is leaking when the canister is full

• Contaminated mass airflow (MAF) sensor (if equipped)

• Damaged MAF sensor (if equipped)

Diagnostic Aids: View the freeze frame data to determine the operating conditions when the DTC was set. Observe the

LONGFT1 and LONGFT2 PIDs. Refer to Section 2, Adaptive Fuel Diagnostic Trouble Code (DTC) Diagnostic Techniques, for additional information and the appropriate pinpoint test for specific concern identification.

Application Key On Engine Off Key On Engine Running Continuous Memory

All GO to Pinpoint Test H.

P0174 - System Too Lean (Bank 2)

Description: The adaptive fuel strategy continuously monitors the fuel delivery hardware. This DTC sets when the adaptive

fuel tables reach a rich calibrated limit. Refer to Section 1, Powertrain Control Software, Fuel Trim for additional information.

Possible Causes: • Ethanol content in the fuel

• Fuel filter plugged or dirty

• Damaged or worn fuel pump

• Leaking fuel pump check valve

• Leaking or contaminated fuel injectors

• Low fuel pressure or running out of fuel

• EVAP purge valve is leaking when the canister is clean

• Fuel supply line restricted

• Fuel rail pressure (FRP) sensor bias

• Exhaust leaks in the exhaust manifold gasket or mating gaskets before or near the heated oxygen sensor

(HO2S)

• Air leaks after the mass airflow (MAF) sensor (if equipped)

• Vacuum leaks

• Positive crankcase ventilation (PCV) system is leaking or the valve is stuck open

• Incorrectly seated engine oil dipstick

• Intake air turbulence due to incorrect air filter

• Contaminated MAF sensor (if equipped)

• Damaged MAF sensor (if equipped)

Diagnostic Aids: View the freeze frame data to determine the operating conditions when the DTC was set. Observe the

LONGFT1 and LONGFT2 PIDs. Refer to Section 2, Adaptive Fuel Diagnostic Trouble Code (DTC) Diagnostic Techniques, for additional information and the appropriate pinpoint test for specific concern identification.

Application Key On Engine Off Key On Engine Running Continuous Memory

All GO to Pinpoint Test H.

P0175 - System Too Rich (Bank 2)

Description: The adaptive fuel strategy continuously monitors the fuel delivery hardware. This DTC sets when the adaptive

fuel tables reach a lean calibrated limit. Refer to Section 1, Powertrain Control Software, Fuel Trim for additional information.

Possible Causes: • Leaking fuel injectors

• Fuel return line restricted

• Fuel rail pressure (FRP) sensor bias

• EVAP purge valve is leaking when the canister is full

• Contaminated mass airflow (MAF) sensor (if equipped)

• Damaged MAF sensor (if equipped)

Diagnostic Aids: View the freeze frame data to determine the operating conditions when the DTC was set. Observe the

LONGFT1 and LONGFT2 PIDs. Refer to Section 2, Adaptive Fuel Diagnostic Trouble Code (DTC) Diagnostic Techniques, for additional information and the appropriate pinpoint test for specific concern identification.

Application Key On Engine Off Key On Engine Running Continuous Memory

All GO to Pinpoint Test H.

P017C - Cylinder Head Temperature Sensor Circuit Low

Description: This DTC sets when the CHT circuit is shorted to ground.

Possible Causes: • CHT circuit short to ground

2016 Powertrain Control/Emissions Diagnosis, Gasoline Engines, 3/2015