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DTCS P1456 & P1457 - EVAP Control

NOTE: DTC P1456 indicates evaporative emission control system leak detected in fuel tank system. DTC P1457 indicates evaporative emission control system leak detected in canister system.
  1. Disconnect vacuum hose from EVAP 3-way valve and connect vacuum pump to hose. See Fig 1 . Turn ignition on and apply vacuum to hose. If vacuum is not maintained, go to next step. If vacuum is maintained, disconnect vent shut valve harness connector. If vacuum is maintained, replace vent shut valve. If vacuum is not maintained, repair short in wire between vent shut valve and PCM connector terminal A29. See Figure . See WIRING DIAGRAMS  section.
  2. Turn ignition off. Connect jumper wire between ground and PCM connector terminal A29. See Figure . Turn ignition on and apply vacuum to vacuum hose. If vacuum is maintained, go to step 4). If vacuum is not maintained, turn ignition off. Disconnect vent shut valve harness connector. Turn ignition on. Measure voltage between ground and vent shut valve harness connector Black/Yellow wire. If battery voltage does not exist, repair open in wire between vent shut valve and power source. See WIRING DIAGRAMS  section.
  3. If battery voltage exists, turn ignition off and reconnect vent shut valve connector. Turn ignition on. Measure voltage between PCM connector terminals A10 and A29. See Figure . If battery voltage does not exist, repair open in wire between vent shut valve and PCM connector terminal A29. See WIRING DIAGRAMS  section. If battery voltage exists, replace vent shut valve.
  4. Reconnect vacuum hose to EVAP 3-way valve. Disconnect vacuum hose from EVAP canister and attach vacuum gauge to disconnected hose. See Fig 1 . Start engine and allow to idle. Engine temperature must be below 167°F (75°C). Quickly raise engine speed to 3000 RPM and observe vacuum gauge. If vacuum does not exist, go to step 7). If vacuum exists, disconnect EVAP purge control solenoid harness connector.
    Fig 1: EVAP Control Canister (Civic)
    G96A09604Courtesy of AMERICAN HONDA MOTOR CO., INC.
  5. Quickly raise engine speed to 3000 RPM and observe vacuum gauge. If vacuum exists, inspect vacuum hose routing. If okay, replace EVAP purge control solenoid. If vacuum does not exist, turn ignition off. Disconnect PCM connector "A". See Figure . Check for continuity between ground and EVAP purge control solenoid harness connector Red/Yellow wire.
  6. If continuity does not exist, repair short in Red/Yellow wire between EVAP purge control solenoid connector and PCM connector "A". See WIRING DIAGRAMS  section. If continuity exists, substitute a known-good PCM and recheck. If symptom or problem goes away, replace original PCM.
  7. Raise and hold engine speed at 3000 RPM, with no load and transmission in Park or Neutral, until radiator fan comes on. Let engine idle. Quickly raise engine speed to 3000 RPM and observe vacuum gauge. If vacuum exists, Go to step 10). If vacuum does not exist, turn ignition off. Disconnect EVAP purge control solenoid harness connector. Start engine. Measure voltage between EVAP purge control solenoid harness connector terminals. If battery voltage exists, go to next step. If battery voltage does not exist, check vacuum house routing. If vacuum is okay, replace EVAP purge control solenoid.
  8. Measure voltage between ground and EVAP purge control solenoid harness connector Yellow/Black wire (Black/Yellow on Civic). If battery voltage does not exist, repair open in Yellow/Black wire (Black/Yellow on Civic) between EVAP purge control solenoid harness connector and fuse No. 15 (7.5 amp) ALTERNATOR SP SENSOR. See WIRING DIAGRAMS  section. If battery voltage exists, turn ignition off.
  9. Reconnect EVAP purge control solenoid connector. Turn ignition on Measure voltage between PCM connector terminals A10 and A15. See Figure . If battery voltage does not exist, repair open in Red/Yellow between EVAP purge control solenoid and PCM. See WIRING DIAGRAMS  section. If battery voltage exists, substitute a known-good PCM and recheck. If symptom or problem goes away, replace original PCM.
  10. Check EVAP 2-way valve. See EMISSION SYSTEMS & SUB SYSTEMS in SYSTEM/COMPONENT TESTS article. Replace valve if faulty. If EVAP 2-way valve is okay, disconnect vacuum hose from EVAP 2-way valve and connect vacuum pump to hose. See Fig 2 . Apply vacuum to hose. If vacuum is maintained, go to next step. If vacuum is not maintained, disconnect EVAP bypass solenoid valve harness connector and reapply vacuum. If vacuum is maintained, repair short in wire between EVAP bypass solenoid valve connector and PCM. See WIRING DIAGRAMS  section. If vacuum is not maintained, replace EVAP bypass solenoid valve.
    Fig 2: EVAP Control 2-Way Valve (Civic)
    G96F09606Courtesy of AMERICAN HONDA MOTOR CO., INC.
  11. Turn ignition off. Connect jumper wire between ground and PCM connector terminal A28. See Figure . Turn ignition on and reapply vacuum. If vacuum is maintained, go to next step. If vacuum is not maintained, check the following for leakage to atmosphere, and repair or replace as necessary: fuel tank, fuel vapor pipe, 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.
  12. Turn ignition off. Disconnect EVAP bypass solenoid valve harness connector. Turn ignition. Measure voltage between ground and EVAP bypass solenoid harness connector Black/Yellow wire (Black/White wire on Civic). If battery voltage does not exist, repair open in wire between EVAP bypass solenoid harness connector and fuse No. 4 (7.5 amp) ECU or fuse No. 15 (7.5 amp) ALTERNATOR SP SENSOR (Civic). See WIRING DIAGRAMS  section.
  13. If battery voltage exists, turn ignition off. Reconnect EVAP bypass solenoid valve connector. Turn ignition on. Measure voltage between PCM connector terminals A10 and A28. See Figure . If battery voltage exists, replace EVAP bypass solenoid valve. If battery voltage does not exist, repair open in wire between EVAP solenoid valve connector and PCM connector A28. See WIRING DIAGRAMS  section.
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