DTC Troubleshooting: P0171 (45), P0172 (45)

DTC P0171:  Fuel System Too Lean
  
  



NOTE: If some of the DTCs listed below are stored at the same time as DTC P0171 and/or P0172, troubleshoot those DTCs first, then recheck for P0171 and/or P0172.

P0107, P0108: Manifold absolute pressure (MAP) sensor
P0133, P1157, P2195, P2238, P2252, P2A00: Air fuel ratio (A/F) sensor (Sensor 1)
P0134, P0135: Air fuel ratio (A/F) sensor (Sensor 1) heater
P0137, P0138, P0139: Secondary HO2S (Sensor 2)
P0141: Secondary HO2S (Sensor 2) heater
P2646, P2647, P2648, P2649: VTEC system

1.Check the following parts for vacuum leaks:
  • PCV valve
  • PCV hose
  • EVAP canister purge valve
  • Throttle body
  • Brake booster hose

Are the parts OK?


YES - Go to 2.


NO - Repair or replace parts with leaks, then go to 6.

2.Check the fuel pressure.

Is the fuel pressure OK?


YES - Check the valve clearances and adjust if necessary. If the valve clearances are OK, replace the injectors, then go to 3.


NO - Check these items:


3.Turn the ignition switch ON (II).

4.Do the ECM/PCM RESET in the CLEAR MENU with the Honda PGM tester or the HDS.

5.Do the ECM/PCM idle learn procedure .

6.Start the engine. Hold the engine speed at 3,000 rpm (min-1) with no load (in Park or neutral until the radiator fan comes on, then let in idle.

7.Test-drive under the following conditions.
  • Engine coolant temperature more than 70°C (158°F)
  • Transmission in 5th gear (A/T in D position)
  • Drive at a steady speed between 24 - 120 km/h (15 - 75 mph)

NOTE: DTC P0171 and/or P0172 may take up to 40 minutes of test driving to set. Using the Honda PGM tester or the HDS, monitor the long term fuel trim (LTFT) or air fuel feed back AVE (AF FB AVE) for 15 minutes of driving. If the fuel trim/AF AVE stays within 10% of 1.0 (0.0%), there in no problem at this time.

8.Check for Temporary DTCs or DTCs in the DTCs MENU with the Honda PGM Tester or the HDS.

Are any Temporary DTCs or DTCs indicated?


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


NO - Troubleshooting is complete.n