LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Acura >> 2003 >> 3.2CL Base >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Performance System Self-Diagnostics >> Diagnostic Tests >> DTC P1456: Evaporative Emission Control System Leak Detected (Fuel Tank System)
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P1456: Evaporative Emission Control System Leak Detected (Fuel Tank System)

  1. Inspect fuel filler cap and seal. Cap must be Gray OEM type and be tightened at least three clicks to seal system. Replace if necessary. If fuel filler cap is okay, go to next step.
    NOTE: EVAP purge control solenoid valve may also be referred to as EVAP canister purge valve.
  2. Turn ignition switch off. Disconnect vacuum hose from EVAP canister purge valve. Connect vacuum pump to now available port on EVAP canister purge valve. See Fig 1 . Turn ignition switch on. Apply vacuum to EVAP canister purge valve. If valve does not hold vacuum, go to next step. If valve holds vacuum, EVAP canister purge valve is okay. Go to step  5 .
  3. Turn ignition switch off. Disconnect EVAP canister purge valve 2-pin harness connector. Check for continuity between ground and EVAP canister purge valve 2-pin harness connector terminal No. 1 (Red/Yellow wire). See appropriate wiring diagram under ENGINE PERFORMANCE in WIRING DIAGRAMS. Repair as necessary. If continuity is present, go to next step. If continuity is not present, replace EVAP canister purge valve.
  4. Disconnect PCM 32-pin "A" harness connector (A/T) or PCM 31-pin "E" harness connector (M/T). Check for continuity between ground and EVAP canister purge valve 2-pin harness connector terminal No. 1 (Red/Yellow wire). If continuity is present, repair short in Red/Yellow wire between EVAP canister purge valve 2-pin harness connector and PCM 32-pin "A" harness connector terminal No. 6 (A/T) or PCM 31-pin "E" harness connector terminal No.11 (M/T). See Figure or Figure . If continuity is not present, substitute known-good PCM, then recheck. If symptom or indication goes away, replace original PCM.
  5. Disconnect vacuum hoses coming from EVAP 2-way valve. Connect vacuum pump and hose to port on EVAP 2-way valve. See Fig 2 . Connect fused jumper wire between ground and PCM 32-pin "A" harness connector terminal No. 3 (Blue wire - A/T) or PCM 31-pin "E" harness connector terminal No.23 (M/T). Turn ignition switch on. Apply vacuum to hose. If EVAP 2-way valve holds vacuum, go to next step. If valve does not hold vacuum, go to step  8 .
  6. Turn ignition switch off. Disconnect EVAP by-pass solenoid valve 2-pin harness connector. Check for continuity between ground and EVAP by-pass solenoid valve 2-pin harness connector terminal No. 2 (Blue wire). See appropriate wiring diagram under ENGINE PERFORMANCE in WIRING DIAGRAMS. If continuity is present, go to next step. If continuity is not present, repair open circuit between PCM 32-pin "A" harness connector terminal No. 3 (Blue wire - A/T) or PCM 31-pin "E" harness connector terminal No.23 (M/T) and EVAP by-pass solenoid valve 2-pin harness connector terminal No. 2.
  7. Turn ignition switch on. Measure voltage between ground and EVAP by-pass solenoid valve 2-pin harness connector terminal No. 1 (Black/Yellow wire). If battery voltage is present, replace EVAP by-pass solenoid valve and "O" rings. If battery voltage is not present, repair open in Black/Yellow wire between EVAP by-pass solenoid valve 2-pin harness connector terminal No. 1 and No. 6 ECU (PCM) CRUISE CONTROL fuse (15-amp) in driver's under-dash fuse/relay box.
  8. Plug upper port of EVAP 2-way valve. See Fig 2 . Monitor Fuel Tank Pressure (FTP) sensor with scan tool or measure voltage between PCM 32-pin "A" harness connector terminal No. 29 (Light Green wire) and 31-pin "C" harness connector terminal No. 18 (Green/Yellow wire - A/T) or PCM 31-pin "E" harness connector terminal No. 28 (Light Green wire) and 31-pin "A" harness connector terminal No. 28 (Green/Yellow wire - M/T) while slowly applying vacuum. See Figure or Figure . If voltage drops to about 1.5 volts and holds for at least 20 seconds, EVAP by-pass solenoid valve/EVAP 2-way valve is okay. Go to next step. If voltage does not drop to about 1.5 volts and hold, repair leakage from EVAP by-pass solenoid valve, EVAP 2-way valve, FTP sensor and "O" rings.
  9. Disconnect vacuum hose from EVAP canister filter. Connect vacuum pump to disconnected hose. Turn ignition switch on. Apply vacuum to hose with 5 strokes of vacuum pump. If EVAP canister vent shut valve holds vacuum, go to next step. If valve does not hold vacuum, EVAP canister vent shut valve is okay. Go to FUEL TANK VAPOR CONTROL VALVE TEST  .
  10. Turn ignition switch off. Disconnect EVAP canister vent shut valve 2-pin harness connector. Check for continuity between ground and EVAP canister vent shut valve 2-pin connector terminal No. 2 (Light Green/White wire). See appropriate wiring diagram under ENGINE PERFORMANCE in WIRING DIAGRAMS. If continuity is present, go to next step. If continuity is not present, replace EVAP canister vent shut valve and "O" ring.
  11. Disconnect PCM 32-pin "A" harness connector (A/T) or PCM 31-pin "E" harness connector (M/T). Check for continuity between ground and EVAP canister vent shut valve 2-pin harness connector terminal No. 2 (Light Green/White wire). If continuity is present, repair short in Light Green/White wire between PCM 32-pin "A" harness connector terminal No. 4 (A/T) or PCM 31-pin "E" harness connector terminal No. 22 (M/T) and EVAP control canister vent shut valve 2-pin harness connector terminal No. 2. If continuity is not present, substitute known-good PCM, then recheck. If symptom or indication goes away, replace original PCM.
  12. Perform FUEL TANK VAPOR CONTROL VALVE TEST  . If fuel tank vapor control valve function properly, go to next step. If valve did not function properly, replace fuel tank vapor control valve.
  13. Tighten fuel filler cap 3 clicks. Connect scan tool to vehicle. Start and idle engine for 5 minutes. Using scan tool, check FTP sensor reading. If fuel tank pressure sensor reading is more than 4 mm Hg pressure or less than 4 mm Hg vacuum, substitute known-good PCM, then recheck. If symptom or indication goes away, replace original PCM. If fuel tank pressure sensor reading is not within specifications, check for leaks at following components:
    • Fuel tank.
    • Fuel filler cap.
    • Fuel filler pipe.
    • Fuel tank vapor control valve.
    • Fuel tank vapor recirculation valve.
    • Fuel tank vapor recirculation tube.
    • Fuel tank vapor signal tube.
    • Fuel tank vapor control vent tube.

    If necessary, repair or replace parts.

Fig 1: Testing EVAP Canister Purge Valve
G00110190Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig 2: Vacuum Testing EVAP 2-Way Valve
G00110195Courtesy of AMERICAN HONDA MOTOR CO., INC.
scientia non olet · About LEMON Manuals