P0172

NOTE: This DTC requires two "trips" or two driving cycles unless the SCS service connector is connected.

P0172 - The scan tool indicates Diagnostic Trouble Code (DTC) P0172 - The fuel system is too rich [Right Bank (Bank 1)].

Description
By monitoring the Long Term Fuel Trim, long term malfunctions in the fuel system will be detected.

If a malfunction has been detected during two consecutive trips, the MIL will come on and DTC P0172 will be stored.

NOTE: If some of the DTCs listed below are stored at the same time as DTC P0172, troubleshoot those DTCs first, then troubleshoot DTC P0172.

P0107, P0108, P1128, P1129 - MAP Sensor
P0135 - Right Primary HO2S Heater (Bank 1, Sensor 1)
P0137, P0138 - Secondary HO2S (Sensor 2)
P0141 - Secondary HO2S Heater (Sensor 2)
P0155 - Left Primary HO2S Heater (Bank 2, Sensor 1)
P0401 - EGR Flow Insufficient
P1491 - EGR Valve Lift Insufficient
P1498 - EGR Valve Position Sensor High Voltage

Possible Cause

DTC P0172, P0175 System Too Rich
- Fuel Pressure Regulator clogged, stuck closed
- Fuel Return Pipe clogged
- Injector leaking
- Gasoline doesn't meet Owner's Manual spec.
- Primary HO2S (Sensor 1) deteriorated
- EGR System malfunction (too much flow)
- EVAP Canister Purge Valve leaking, stuck opened

Troubleshooting Flowchart: