DTC P0172, P0175: Fuel System Too Rich (2013-15)

DTC P0172  : Rear Bank (Bank 1) Fuel System Too Rich DTC P0175  : Front Bank (Bank 2) Fuel System Too Rich

DTC (PGM-FI)

1. Problem verification-Idle:

   Start the engine, and let it idle without load (in P or N).

   - 2. Check the parameter(s) below with the HDS.

   Signal	Threshold	Current conditions
   Values	Unit	Values	Unit
   ST FUEL TRIM B1	Less than 0.73
   ST FUEL TRIM B2	Less than 0.73

   Do the current condition(s) match the threshold?

   YES 

   The ST FUEL TRIM (B1, B2) is too low at idle. Go to step 3.

   NO 

   The ST FUEL TRIM (B1, B2) is OK at idle. Go to step 2.

2. Problem verification-On-board Snapshot:

   Review the on-board snapshot and record the value of the parameters below when ST FUEL TRIM (B1, B2) was at its lowest point.

   ENGINE SPEED
   VEHICLE SPEED
   REL TP SENSOR

   APP SENSOR

   On-board Snapshot

   - 2. Drive the vehicle according to the conditions determined above.

   Signal	Current conditions
   Values	Unit
   ENGINE SPEED
   VEHICLE SPEED
   REL TP SENSOR
   APP SENSOR

   - 3. Check the parameter(s) below with the HDS while driving.

   Signal	Threshold	Current conditions
   Values	Unit	Values	Unit
   ST FUEL TRIM B1	Less than 0.73
   ST FUEL TRIM B2	Less than 0.73

   Do the current condition(s) match the threshold under the on-board snapshot conditions?

   YES 

   ST FUEL TRIM (B1, B2) is too low under the conditions above. Go to step 3.

   NO 

   ST FUEL TRIM (B1, B2) is OK under the same conditions as the on-board snapshot. The system is normal at this time.

3. Check for MAF Sensor Debris:

   Remove the MAF sensor/IAT sensor.

   - 2. Check for lint, bugs, and other foreign objects in the sensor.

   Is there debris in the MAF sensor?

   YES 

   Remove the debris from the MAF sensor and then use a vacuum cleaner to remove any debris from the air cleaner housing, then do the repair verification.

   NO 

   Reinstall the MAF sensor/IAT sensor . Go to step 4.

4. Check Fuel Pressure:

   Check the fuel pressure under the conditions when ST FUEL TRIM (B1, B2) is 0.73 or less.

   Signal	Current conditions
   Values	Unit
   ST FUEL TRIM B1
   ST FUEL TRIM B2

   Is the fuel pressure between 390-440 kPa (4.0-4.5 kgf/cm

   ²

   , 57-64 psi)-

   YES 

   The fuel pressure is OK. Go to step 5.

   NO 

   Replace the fuel tank unit , then do the repair verification.

5. Check MAF Sensor Reading:

   Start the engine and hold the engine speed at 3, 000 rpm until the radiator fan comes on.

   - 2. Make sure the following conditions are met:

   • ECT Sensor 1 above 158 °F (70 °C)
   • Transmission in P or N
   • All engine and electrical loads turned off

   Signal	Current conditions
   Values	Unit
   ECT SENSOR 1

   - 3. Monitor the ENGINE SPEED in the DATA LIST with the HDS, then hold the engine speed at 2, 500 rpm with the accelerator pedal held steady.

   Signal	Current conditions
   Values	Unit
   ENGINE SPEED

   - 4. Check the parameter(s) below with the HDS at 2, 500 rpm.

   Signal	Threshold	Current conditions
   Values	Unit	Values	Unit
   MAF SENSOR	9.1-12.7	g/s

   Do the current condition(s) match the threshold?

   YES 

   The MAF sensor is OK. Go to step 6.

   NO 

   The MAF sensor is reading incorrectly. Inspect for a cracked, damaged, or incorrectly installed air cleaner assembly. If OK, replace the MAF sensor/IAT sensor , then do the repair verification.

6. Check Engine Oil:

   Start the engine, and let it idle.

   - 2. Gently pinch the PCV vacuum hose (A).

   Courtesy of HONDA, U.S.A., INC.

   - 3. Check the parameter(s) below with the HDS with the vacuum hose pinched.

   Signal	Threshold	Current conditions
   Values	Unit	Values	Unit
   ST FUEL TRIM B1	Less than 0.73
   ST FUEL TRIM B2	Less than 0.73

   Do the current condition(s) match the threshold?

   YES 

   The engine oil is OK. Go to step 7.

   NO 

   The engine oil is contaminated. Replace the engine oil and oil filter , then do the repair verification.

7. Replace Fuel Injectors:

   Replace the fuel injectors with known-good injectors.

   - 2. Operate the vehicle under the same conditions where ST FUEL TRIM (B1, B2) was 0.73 or less.

   ENGINE SPEED
   VEHICLE SPEED
   REL TP SENSOR
   APP SENSOR

   On-board Snapshot

   Signal	Current conditions
   Values	Unit
   ENGINE SPEED
   VEHICLE SPEED
   REL TP SENSOR
   APP SENSOR

   - 3. Check the parameter(s) below with the HDS while driving.

   Signal	Threshold	Current conditions
   Values	Unit	Values	Unit
   ST FUEL TRIM B1	Less than 0.73
   ST FUEL TRIM B2	Less than 0.73

   Do the current condition(s) match the threshold under the on-board snapshot conditions?

   YES 

   The fuel injectors are not the cause of the low ST FUEL TRIM (B1, B2) value. Go to step 8.

   NO 

   The fuel injectors were causing the low ST FUEL TRIM (B1, B2) value. Replace the original injectors , then do the repair verification.

8. Replace A/F Sensor (Sensor 1)

   Replace the A/F sensor (Sensor 1) with a known-good sensor.

   - 2. Operate the vehicle under the same conditions where ST FUEL TRIM (B1, B2) was 0.73 or less.

   ENGINE SPEED

   VEHICLE SPEED
   REL TP SENSOR
   APP SENSOR

   On-board Snapshot

   Signal	Current conditions
   Values	Unit
   ENGINE SPEED
   VEHICLE SPEED
   REL TP SENSOR
   APP SENSOR

   - 3. Check the parameter(s) below with the HDS while driving.

   Signal	Threshold	Current conditions
   Values	Unit	Values	Unit
   ST FUEL TRIM B1	Less than 0.73
   ST FUEL TRIM B2	Less than 0.73

   Do the current condition(s) match the threshold under the on-board snapshot conditions?

   YES 

   The A/F sensor (Sensor 1) is not the cause of the low ST FUEL TRIM (B1, B2) value. Go to step 9.

   NO 

   The A/F sensor (Sensor 1) was causing the low ST FUEL TRIM (B1, B2) value. Replace the original A/F sensor (Sensor 1) , then do the repair verification.

9. Replace Fuel:
   NOTE: There is an increased likelihood of a fuel related issue if the misfire appeared shortly after refueling. The MIL DIST (MIL Distance) value in the DATA LIST in combination with the fuel level may help you make this determination.

   Remove the fuel tank unit and then drain and refill the fuel tank with known-good fuel.

   - 2. Operate the vehicle under the same conditions where ST FUEL TRIM (B1, B2) was 0.73 or less.

   ENGINE SPEED
   VEHICLE SPEED
   REL TP SENSOR
   APP SENSOR

   On-board Snapshot

   Signal	Current conditions
   Values	Unit
   ENGINE SPEED
   VEHICLE SPEED
   REL TP SENSOR
   APP SENSOR

   - 3. Check the parameter(s) below with the HDS while driving.

   Signal	Threshold	Current conditions
   Values	Unit	Values	Unit
   ST FUEL TRIM B1	Less than 0.73
   ST FUEL TRIM B2	Less than 0.73

   Do the current condition(s) match the threshold under the on-board snapshot conditions?

   YES 

   The fuel is not the cause of the low ST FUEL TRIM (B1, B2) value. Substitute a known-good PCM , then do the repair verification.

   NO 

   The fuel was causing the low ST FUEL TRIM (B1, B2) value. Do the repair verification.

10. Repair verification:

    - 1. Press the engine start/stop button to select the ON mode.

    - 2. Reset the PCM with the HDS - Refer to: How to Troubleshoot the Fuel and Emissions Systems (2013-15), or How to Troubleshoot the A/T System (2013-15) .

    Reset PCM

    - 3. Do the PCM idle learn procedure.

    - 4. Start the engine. Hold the engine speed at 3, 000 rpm without load (in P or N) until the radiator fan comes on, then let it idle.

    - 5. Operate the vehicle under the same conditions where ST FUEL TRIM (B1, B2) was 0.73 or less.

    ENGINE SPEED
    VEHICLE SPEED
    REL TP SENSOR
    APP SENSOR

    On-board Snapshot

    Signal	Current conditions
    Values	Unit
    ENGINE SPEED
    VEHICLE SPEED
    REL TP SENSOR
    APP SENSOR

    - 6. Check the parameter(s) below with the HDS while driving.

    Signal	Threshold	Current conditions
    Values	Unit	Values	Unit
    ST FUEL TRIM B1	Less than 0.73
    ST FUEL TRIM B2	Less than 0.73

    Do the current condition(s) match the threshold under the on-board snapshot conditions?

    YES 

    ST FUEL TRIM (B1, B2) is too low. Go to step 3.

    NO 

    ST FUEL TRIM (B1, B2) is OK. Troubleshooting is complete.