DTC P0497: EVAP System Low Purge Flow

Special Tools Required 

Vacuum pump/gauge, 0-30 in.Hg A973X-041-XXXXX

1. Turn the ignition switch ON (II).
2. Measure voltage between ECM/PCM connector terminal B21 and body ground.
   Fig 1: Measuring Voltage Between ECM/PCM Connector Terminal B21 & Body Ground

   Courtesy of AMERICAN HONDA MOTOR CO., INC.

   Is there battery voltage? 

   1. YES  - Go to step 3.
   2. NO  - Go to step  8.
3. Turn the ignition switch OFF.
4. Disconnect the vacuum hose (A) from the EVAP canister purge valve (B) and connect a vacuum pump/gauge to the hose.
   Fig 2: Disconnecting Vacuum Hose From EVAP Canister Purge Valve

   Courtesy of AMERICAN HONDA MOTOR CO., INC.
5. Connect the ECM/PCM connector terminal B21 to body ground with a jumper wire.
   Fig 3: Connecting ECM/PCM Connector Terminal B21 To Body Ground

   Courtesy of AMERICAN HONDA MOTOR CO., INC.
6. Turn the ignition switch ON (II).
7. Apply vacuum to the hose.

   Does the valve hold vacuum? 

   1. YES  - Replace the EVAP canister purge valve (see THROTTLE BODY DISASSEMBLY/REASSEMBLY ).
   2. NO  - Go to step  16.
8. Turn the ignition switch OFF.
9. Disconnect the ECM connector B (24P).
10. Connect the ECM/PCM connector terminal B21 to body ground with a jumper wire.
    Fig 4: Connecting ECM/PCM Connector Terminal B21 To Body Ground

    Courtesy of AMERICAN HONDA MOTOR CO., INC.
11. Disconnect the EVAP canister purge valve 2P connector.
12. Check for continuity between the EVAP canister purge valve 2P connector terminal No. 2 and body ground.
    Fig 5: Checking Continuity Between EVAP Canister Purge Valve 2-Pin Connector Terminal No. 2 & Body Ground

    Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Go to step 13.
    2. NO  - Repair open in the wire between the EVAP canister purge valve and the ECM/PCM (B21).
13. Turn the ignition switch ON (II).
14. Measure voltage between the EVAP canister purge valve 2P connector terminal No. 1 and body ground.
    Fig 6: Measuring Voltage Between EVAP Canister Purge Valve 2-Pin Connector Terminal No. 1 & Body Ground

    Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    1. YES  - Go to step 15.
    2. NO  - Repair open in the wire between the EVAP canister purge valve and the No. 4 ACG (10A) fuse in the under-dash fuse/relay box.
15. Measure resistance between the EVAP canister purge valve 2P connector terminals No. 1 and No. 2.
    Fig 7: Measuring Resistance Between EVAP Canister Purge Valve 2-Pin Connector Terminals No. 1 & No. 2

    Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there about 33 ohm at room temperature? 

    1. YES  - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM UPDATING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
    2. NO  - Replace the EVAP canister purge valve (see THROTTLE BODY DISASSEMBLY/REASSEMBLY ).
16. Measure voltage between ECM/PCM connector terminal E21 and body ground.
    Fig 8: Measuring Voltage Between ECM/PCM Connector Terminal E21 & Body Ground

    Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    1. YES  - Go to step 17.
    2. NO  - Go to step  22.
17. Turn the ignition switch OFF.
18. Disconnect the vacuum hose from the EVAP canister vent filter line (A), and connect a vacuum pump/gauge to the hose.
    Fig 9: Disconnecting Vacuum Hose From EVAP Canister Vent Filter Line

    Courtesy of AMERICAN HONDA MOTOR CO., INC.
19. Connect the ECM/PCM connector terminal E21 to body ground with a jumper wire.
    Fig 10: Connecting ECM/PCM Connector Terminal E21 To Body Ground

    Courtesy of AMERICAN HONDA MOTOR CO., INC.
20. Turn the ignition switch ON (II).
21. Apply vacuum to the hose.

    Does the valve hold vacuum? 

    1. YES  - Inspect the vacuum line between the EVAP canister purge valve and the EVAP canister.
    2. NO  - Replace the EVAP canister vent shut valve (see THROTTLE BODY DISASSEMBLY/REASSEMBLY ).
22. Turn the ignition switch OFF.
23. Disconnect the ECM connector E (31P).
24. Connect the ECM/PCM connector terminal E21 to body ground with a jumper wire.
    Fig 11: Connecting ECM/PCM Connector Terminal E21 To Body Ground

    Courtesy of AMERICAN HONDA MOTOR CO., INC.
25. Disconnect the EVAP canister vent shut valve 2P connector.
26. Check for continuity between the EVAP canister vent shut valve 2P connector terminal No. 2 and body ground.
    Fig 12: Checking Continuity Between EVAP Canister Vent Shut Valve 2-Pin Connector Terminal No. 2 & Body Ground

    Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Go to step 27.
    2. NO  - Repair open in the wire between the EVAP canister vent shut valve and the ECM/PCM (E21).
27. Turn the ignition switch ON (II).
28. Measure voltage between the EVAP canister vent shut valve 2P connector terminal No. 1 and body ground.
    Fig 13: Measuring Voltage Between EVAP Canister Vent Shut Valve 2-Pin Connector Terminal No. 1 & Body Ground

    Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    1. YES  - Go to step 29.
    2. NO  - Repair open in the wire between the EVAP canister vent shut valve and the No. 4 ACG (10A) fuse in the under-dash fuse/relay box.
29. Measure resistance between the EVAP canister vent shut valve 2P connector terminals No. 1 and No. 2.
    Fig 14: Measuring Resistance Between EVAP Canister Vent Shut Valve 2-Pin Connector Terminals No. 1 & No. 2

    Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there about 33 ohm at room temperature? 

    1. YES  - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM UPDATING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
    2. NO  - Replace the EVAP canister vent shut valve (see step  22. on ).