P0172

DTC P0171: Rear Bank (Bank 1) Fuel System Too Lean

DTC P0172: Rear Bank (Bank 1) Fuel System Too Rich

DTC P0174: Front Bank (Bank 2) Fuel System Too Lean

DTC P0175: Front Bank (Bank 2) Fuel System Too Rich

NOTE:
- If some of the DTCs listed below are stored at the same time as DTC P0171, P0172, P0174, and/or P0175, troubleshoot those DTCs first, then recheck for P0171, P0172, PO174, and/or P0175.
P0107, P0108, P1128, P1129: Manifold absolute pressure (MAP) sensor.
P0133, P0153, P2195, P2197, P2237, P2238, P2240, P2241, P2243, P2245, P2247, P2249, P2251, P2252, P2254, P2255, P2627, P2628, P2630, P2631, P2A00, P2A03: Air fuel ratio (A/F) sensor (Sensor 1).
P0134, P0135, P0154, PO155: Air fuel ratio (A/F) sensor (Sensor 1) heater.
P0137, P0138, P0139, PO157, P0158, P0159: Secondary HO2S (Sensor 2)
P0141, P0161: Secondary HO2S (Sensor 2) heater
P2646, P2647, P2648, P2649: VTEC system
P0401, P0404, P0406, P2413: Exhaust gas recirculation (EGR) system.
P2279: Intake air leakage
- Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.

1. Check the fuel pressure.

Is the fuel pressure OK?

YES - Check the valve clearances and adjust if necessary (P0172 and P0175 only). If the valve clearances are OK, replace the injectors, then go to step 2.

NO - Check these items:
- If the pressure is too high, replace the fuel pressure regulator, then go to step 2. If the pressure is too low, check the fuel pump, the fuel pressure regulator and the fuel feed line, then go to step 2.

2. Turn the ignition switch ON (II).
3. Reset the ECM/PCM with the HDS.
4. Do the ECM/PCM idle learn procedure.
5. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on, then let it idle.
6. Test-drive under these conditions:
- Engine coolant temperature above 158 degrees F (70 degrees C)
- A/T in D position ( M/T in 5th gear)
- Drive at a steady speed between 25 - 55 mph (40 - 88 km/h) for 5 minutes, then drive at a steady speed between 15 - 75 mph (24 - 120 km/h) for 15 minutes.

NOTE: DTC P0171, P0172, P0174, and/or P0175 may take up to 80 minutes of test driving to set. Using the HDS, monitor the long term fuel trim (LT FUEL TRIM). If the long term fuel trim within 0.86 - 1.17, there is no problem at this time.

7. Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated.

YES - If DTC P0171, P0172, P0174, or PO175 is indicated, go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.

NO - Troubleshooting is complete.