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DTC P1456 & P1457: EVAP Control System

NOTE: If DTC P1456 sets an EVAP control system leak has been detected in the fuel tank system. If DTC P1457 sets an EVAP control system leak has been detected in the EVAP control canister system.
  1. If either DTC P1456 or DTC P1457 sets check for:
    • A faulty fuel filler cap.
    • Proper vacuum connections.
    • Fuel tank leak.
    • EVAP control canister vent shut valve malfunction.
    • EVAP control canister vent shut valve circuit malfunction.
    • EVAP purge control solenoid valve malfunction.
    • EVAP purge control solenoid valve circuit malfunction.
    • EVAP bypass solenoid valve malfunction.
    • EVAP bypass solenoid valve circuit malfunction.
    • Fuel tank pressure sensor malfunction.
    • Fuel tank pressure sensor circuit malfunction.
    • EVAP control canister malfunction.

    Repair as necessary. If no problems are found, go to next step.

  2. Disconnect vacuum hose from EVAP 3-way valve located on side of EVAP canister. Turn ignition on. Connect vacuum pump to hose and apply vacuum (about 5 pump strokes) to EVAP control canister vent shut valve. If vacuum holds, go to next step. If vacuum does not hold, go to step 4).
  3. Disconnect EVAP control canister vent shut valve 2-pin connector located on top of EVAP control canister. Apply vacuum to EVAP control canister vent shut valve. If vacuum holds, replace EVAP control canister vent shut valve. If vacuum does not hold, repair short in Green/Yellow wire between EVAP control canister vent shut valve and PCM 32-pin connector terminal No. 29. See Figure.
  4. Turn ignition off. Using a jumper wire, connect PCM 32-pin connector terminal No. 29 (Green/Yellow wire) to ground. Turn ignition on. Apply vacuum to EVAP control canister vent shut valve. If vacuum does not hold, go to next step. If vacuum holds, go to step 7).
  5. Turn ignition off. Disconnect EVAP control canister vent shut valve 2-pin connector. Turn ignition on. Measure voltage between ground and EVAP control canister vent shut valve 2-pin connector terminal No. 1 (Black/Yellow wire). If battery voltage is present, go to next step. If battery voltage is not present, repair open in Black/Yellow wire between EVAP control canister vent shut valve and ECU, EAT ECU, CRUISE CONTROL, FAN TIMER fuse No. 4 (7.5-amp), located in underdash fuse/relay box.
  6. Turn ignition off. Reconnect EVAP control canister vent shut valve 2-pin connector. Turn ignition on. Measure voltage between PCM 32-pin connector terminals No. 10 (Black wire) and No. 29 (Green/Yellow wire). See Figure. If battery voltage is present, replace EVAP control canister vent shut valve. If battery voltage is not present, repair open in Green/Yellow wire between EVAP control canister vent shut valve and PCM 32-pin connector terminal No. 29.
  7. Disconnect EVAP control canister lower vacuum hose. See Fig 1. Start cold engine and allow to idle. Ensure engine coolant temperature is less than 122°F (50°C). Quickly increase engine speed to 3000 RPM and check for vacuum at EVAP control canister lower vacuum hose. If vacuum is present, go to next step. If vacuum is not present, go to step 10).
  8. Disconnect EVAP purge control solenoid valve 2-pin connector. Quickly increase engine speed to 3000 RPM and check for vacuum at EVAP control canister lower vacuum hose. See Fig 1. If vacuum is not present, go to next step. If vacuum is present, check for incorrect vacuum hose routing. If hose routing is okay, replace EVAP purge control solenoid valve.
    Fig 1: Identifying EVAP Control Canister Components
    G97H06005Courtesy of AMERICAN HONDA MOTOR CO., INC.
  9. Turn ignition off. Disconnect PCM 32-pin connector. See Figure. Check for continuity between ground and EVAP purge control sole noid valve 2-pin connector terminal No. 1 (Red/Yellow wire). If continuity exists, repair short in Red/Yellow wire between EVAP purge control solenoid valve and PCM 32-pin connector terminal No. 15. If continuity does not exist, substitute a known-good PCM and recheck. If DTCs do not reset, replace original PCM.
  10. Start engine and hold at 3000 RPM with no loads and transmission in Park or Neutral, until cooling fan comes on. Allow engine to idle and check for vacuum at EVAP control canister lower vacuum hose. Quickly increase engine speed to 3000 RPM and check for vacuum at EVAP control canister lower vacuum hose again. If vacuum is not present, go to next step. If vacuum is present, go to step 14).
  11. Turn ignition off. Disconnect EVAP purge control solenoid valve. Start engine and allow to idle. Measure voltage between EVAP purge control solenoid valve 2-pin harness connector terminals No. 1 (Red/Yellow wire) and No. 2 (Black/Yellow wire). If battery voltage is not present, go to next step. If battery voltage is present, ensure vacuum hose routing is correct. If vacuum hoses are okay, replace EVAP purge control solenoid valve.
  12. Measure voltage between ground and EVAP purger control solenoid valve 2-pin connector terminal No. 2 (Black/Yellow wire). If battery voltage is present, go to next step. If battery voltage is not present, repair open in Black/Yellow wire between EVAP purger control solenoid valve and ECU, EAT ECU, CRUISE CONTROL, FAN TIMER fuse No. 4 (7.5-amp).
  13. Turn ignition off. Reconnect EVAP purge control solenoid valve 2-pin connector. Turn ignition on. Measure voltage between PCM 32-pin connector terminals No. 10 (Black wire) and No. 15 (Red/Yellow wire). See Figure. If battery voltage is not present, repair open in Red/Yellow wire between EVAP purge control solenoid valve and PCM. If battery voltage is present, substitute a known-good PCM and recheck. If DTCs do not reset, replace original PCM.
  14. Ensure EVAP 2-way valve is operating properly. See the SYSTEM/COMPONENT TESTS article. If EVAP 2-way valve is operating properly, go to next step. Replace EVAP 2-way valve if is not operating properly.
  15. Disconnect both vacuum hoses from EVAP 2-way valve. See Fig 2. Turn ignition on. Apply vacuum to EVAP 2-way valve lower vacuum port. If vacuum holds, go to next step. If vacuum does not hold, disconnect EVAP bypass solenoid valve 2-pin connector. If vacuum does not hold, replace EVAP bypass solenoid valve. If vacuum holds, repair short in Blue wire between EVAP bypass solenoid valve and PCM 32-pin connector terminal No. 28.
    Fig 2: Identifying EVAP 2-Way & Bypass Solenoid Valves
    G97J06006Courtesy of AMERICAN HONDA MOTOR CO., INC.
  16. Turn ignition off. Using a jumper wire, connect PCM 32-pin connector terminal No. 28 (Blue wire) to ground. See Figure. Turn ignition on. If EVAP bypass solenoid valve holds vacuum, go to next step. If EVAP bypass solenoid valve does not hold vacuum, check for leaks to atmosphere, and repair or replace the following components if needed:
    • Fuel filler cap and fuel tank.
    • Fuel vapor line.
    • EVAP 2-way valve.
    • EVAP bypass solenoid valve.
    • Fuel tank pressure sensor.
    • EVAP control canister.
    • EVAP control canister vent shut valve.
    • EVAP purge control solenoid valve.
    • Vacuum hoses and connections.
  17. Turn ignition off. Disconnect EVAP bypass solenoid valve 2-pin connector. Turn ignition on. Measure voltage between ground and EVAP bypass solenoid valve 2-pin connector terminal No. 1 (Black/Yellow wire). If battery voltage is present, go to next step. If battery voltage is not present, repair open in Black/Yellow wire between EVAP bypass solenoid valve and ECU, EAT ECU, CRUISE CONTROL, FAN TIMER fuse No. 4 (7.5-amp).
  18. Turn ignition off. Reconnect EVAP bypass solenoid valve 2-pin connector. Turn ignition on. Measure voltage between PCM 32-pin connector terminal No. 10 (Black wire) and No. 28 (Blue wire). See Figure. If battery voltage is present, replace EVAP bypass solenoid valve. If battery voltage is not present, repair open in Blue wire between EVAP bypass solenoid valve and PCM.
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