DTC P04F1: EVAP System Low Purge Flow Detected (L4)

Special Tools Required 

-Vacuum Pump/Gauge, 0-30 inHg Snap-on YA4000A or equivalent, commercially available

-Vacuum/Pressure Gauge, 0-4 inHg 07JAZ-001000B

NOTE:  Before you troubleshoot, review the general troubleshooting information - Refer to: How to Troubleshoot the Fuel and Emissions Systems (L4) .

DTC (PGM-FI)

1. Problem verification

   -1. Turn the vehicle to the ON mode.

   - 2. Clear the DTC with the HDS.

   - 3. Select the EVAP TEST in the INSPECTION MENU, then select the FUNCTION TEST with the HDS.

   FUNCTION TEST

   Is the result OK?

   YES 

   Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the FTP sensor, the EVAP canister purge valve, the EVAP canister vent shut valve, and the PCM. If the on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the on-board snapshot - Refer to: PGM-FI System Description - Electronic Control , PGM-FI System Description - On-Board Snapshot , and PGM-FI System Description - Components (L4, KA/KC) .

   NO 

   The failure is duplicated. Go to step 2.

2. EVAP canister purge line visual check

   -1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Check for a poor connection, a blockage, or damage at the EVAP canister purge line between the throttle body and the EVAP canister.

   Is the line OK?

   YES 

   Go to step 3.

   NO 

   Reconnect or repair the EVAP canister purge line.

3. Determine possible failure area (EVAP canister purge valve, others)

   -1. Disconnect the vacuum hose (purge line) (A) from the EVAP canister purge valve (B) in the engine compartment, then connect a T-fitting (C), a vacuum gauge, and a vacuum pump/gauge, 0-30 inHg, to the vacuum hose as shown.

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

   - 2. Turn the vehicle to the ON mode.

   - 3. Select the EVAP TEST in the INSPECTION MENU, then select the EVAP PCS ON in the SINGLE SOLENOID with the HDS.

   SINGLE SOLENOID

   Apply about 2 kPa (0.6 inHg, 15 mmHg) of vacuum to the hose.

   Does it hold vacuum?

   YES 

   Replace the EVAP canister purge valve - Refer to: EVAP Canister Purge Valve Removal and Installation (L4) .

   NO 

   Go to step 4.

4. Determine possible failure area (EVAP canister purge line, others)

   -1. Select the EVAP TEST in the INSPECTION MENU, then select the EVAP PCS OFF in the SINGLE SOLENOID with the HDS.

   SINGLE SOLENOID

   Reconnect the vacuum hose to the EVAP canister purge valve.

   - 3. Remove the rear subframe undercover..

   - 4. Disconnect the EVAP canister purge line (A) from the EVAP canister (B). Connect the T-fitting (C), the vacuum gauge, and the vacuum pump/gauge, 0?30 inHg, to the EVAP canister purge line as shown.

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

   - 5. Apply about 2 kPa (0.6 inHg, 15 mmHg) of vacuum to the hose.

   - 6. Select the EVAP PCS ON in the SINGLE SOLENOID with the HDS.

   SINGLE SOLENOID

   Does it hold vacuum?

   YES 

   Check for a blockage in the purge line between the EVAP canister purge valve and the EVAP canister.

   NO 

   Go to step 5.

5. FTP sensor performance check

   -1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Remove the FTP sensor with its connector connected.

   - 3. Connect the T-fitting (A) to the vacuum pump/gauge, 0?30 inHg, and the vacuum gauge to the FTP sensor (B) as shown.

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

   - 4. Turn the vehicle to the ON mode.

   - 5. Check and record the FTP sensor reading in the DATA LIST with the HDS.

   Signal	Current conditions
   	Values	Unit
   FTP SENSOR

   - 6. Slowly apply about 1.3 kPa (0.4 inHg, 10 mmHg) of vacuum to the hose.

   NOTE:  Be careful not to exceed the vacuum. If you do, the FTP sensor can be damaged.

   - 7. Check the FTP SENSOR in the DATA LIST with the HDS.

   Signal	Current conditions
   	Values	Unit
   FTP SENSOR

   Does the value change?

   YES 

   Go to step 6.

   NO 

   Replace the FTP sensor - Refer to: FTP Sensor Removal and Installation (Without SH-AWD, KA/KC) .

6. EVAP canister purge line check

   -1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Reconnect the EVAP canister purge line to the canister, and reinstall the FTP sensor.

   - 3. Disconnect the vacuum hose (purge line) (A) from the EVAP canister purge valve (B) in the engine compartment, then connect the T-fitting (C), the vacuum gauge, and the vacuum pump/gauge, 0?30 inHg, to the vacuum hose as shown.

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

   - 4. Slowly apply about 2 kPa (0.6 inHg, 15 mmHg) of vacuum to the hose.

   Does the hose hold vacuum?

   YES 

   Check for a blockage at the EVAP canister purge line port.

   NO 

   Replace the EVAP canister vent shut valve .