DTC P0497: EVAP System Low Purge Flow (2004-05 Models)

Turn the ignition switch ON (II).
Measure voltage between ECM connector terminal B21 and body ground.

Fig 1: Measuring Voltage Between ECM Connector Terminal B21 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES: Go to step 3.

NO: Go to step 8.
Turn the ignition switch OFF.
Disconnect the vacuum hose (A) from the EVAP canister purge valve (B) and connect commercially available vacuum pump/gauge, 0-3 in. HG (A973X-041-XXXXX or Snap-On YA4000A or equivalent) to the hose.

Fig 2: Connecting A Vacuum Pump/Gauge To The Hose
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Connect the ECM connector terminal B21 to body ground with a jumper wire.

Fig 3: Connecting The ECM Connector Terminal B21 To Body Ground With A Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Turn the ignition switch ON (II).
Apply vacuum to the hose.
Does the valve hold vacuum?

YES: Replace the EVAP canister purge valve (see THROTTLE BODY DISASSEMBLY/REASSEMBLY ).

NO: Go to step 16.
Turn the ignition switch OFF.
Disconnect the ECM connector B (24P).
Connect the ECM connector terminal B21 to body ground with a jumper wire.

Fig 4: Connecting The ECM Connector Terminal B21 To Body Ground With A Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Disconnect the EVAP canister purge valve 2P connector.
Check for continuity between the EVAP canister purge valve 2P connector No. 2 and body ground.

Fig 5: Checking For Continuity Between The EVAP Canister Purge Valve 2P Connector No. 2 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES: Go to step 13.

NO: Repair open in the wire between the EVAP canister purge valve the ECM (B21).
Turn the ignition switch ON (II).
Measure voltage between the EVAP canister purge valve 2P connector terminal No. 1 and body ground.

Fig 6: Measuring Voltage Between The EVAP Canister Purge Valve 2P Connector Terminal No. 1 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES: Go to step 15.

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.
Measure resistance between the EVAP canister purge valve 2P connector terminals No. 1 and No. 2.

Fig 7: Measuring Resistance Between The EVAP Canister Purge Valve 2P Connector Terminals No. 1 And No. 2
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there about 33 Ω at room temperature?

YES: Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck (see ECM UPDATING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM, replace the original ECM.

NO: Replace the EVAP canister purge valve (see THROTTLE BODY DISASSEMBLY/REASSEMBLY ).
Measure voltage between ECM connector terminal E21 and body ground.

Fig 8: Measuring Voltage Between ECM Connector Terminal E21 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES: Go to step 17.

NO: Go to step 22.
Turn the ignition switch OFF.
Disconnect the vacuum hose from the EVAP canister vent filter line (A) and connect a commercially available vacuum pump/gauge, 0-3 in. Hg (A0973X-041-XXXXX

Fig 9: Connecting A Vacuum Pump/Gauge To The Hose
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Connect the ECM connector terminal E21 to body ground with a jumper wire.

Fig 10: Connecting The ECM Connector Terminal E21 To Body Ground With A Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Turn the ignition switch ON (II).
Apply vacuum to the hose.
Does the valve hold vacuum?

YES: Inspect the vacuum line between the EVAP canister purge valve and the EVAP canister.

NO: Replace the EVAP canister vent shut valve.
Turn the ignition switch OFF.
Disconnect the ECM connector E (31P).
Connect the ECM connector terminal E21 to body ground with a jumper wire.

Fig 11: Connecting The ECM Connector Terminal E21 To Body Ground With A Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Disconnect the EVAP canister vent shut valve 2P connector.
Check for continuity between the EVAP canister vent shut valve 2P connector No. 2 and body ground.

Fig 12: Checking For Continuity Between The EVAP Canister Vent Shut Valve 2P Connector No. 2 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES: Go to step 27.

NO: Repair open in the wire between the EVAP canister vent shut valve and the ECM (E21).
Turn the ignition switch ON (II).
Measure voltage between the EVAP canister vent shut valve 2P connector terminal No. 1 and body ground.

Fig 13: Measuring Voltage Between The EVAP Canister Vent Shut Valve 2P Connector Terminal No. 1 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES: Go to step 29.

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.
Measure resistance between the EVAP canister vent shut valve 2P connector terminals No. 1 and No. 2.

Fig 14: Measuring Resistance Between The EVAP Canister Vent Shut Valve 2P Connector Terminals No. 1 And No. 2
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there about 33 Ω at room temperature?

YES: Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck (see ECM UPDATING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM, replace the original ECM.

NO: Replace the EVAP canister vent shut valve.