DTC P1456 & P1457: EVAP System Leak Detected
NOTE:
DTC P1456 indicates Evaporative Emission (EVAP) control system leak detected in fuel tank system. DTC P1457 indicates EVAP control system leak detected in canister system.
NOTE:
Components and/or systems listed in the following steps do not apply to all vehicles, refer to vehicle underhood EMISSION GROUP IDENTIFICATION label for confirmation.
- 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 by-pass solenoid valve malfunction.
- EVAP by-pass 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 found, go to next step.
- Disconnect vacuum hose from EVAP 3-way valve and connect vacuum pump to hose. See Fig 1 . See the VACUUM DIAGRAMS article. Turn ignition on and apply vacuum to hose. If vent shut valve does not hold a vacuum, go to next step. If vent shut valve holds a vacuum, disconnect vent shut valve 2-pin connector. If vent shut valve holds a vacuum, replace vent shut valve. If vent shut valve does not hold a vacuum, repair short in wire between vent shut valve and PCM 32-pin connector "A" terminal A29 (Orange/Green wire). See Figure . See the WIRING DIAGRAMS article.
- Turn ignition off. Connect a fused jumper wire between ground and PCM 32-pin connector "A" terminal A29. See Figure . Turn ignition on and apply vacuum to vent shut valve vacuum hose. If vent shut valve holds a vacuum, go to step 6). If vent shut valve does not hold a vacuum, go to next step.
- Turn ignition off. Disconnect vent shut valve 2-pin connector. Turn ignition on. Measure voltage between ground and vent shut valve 2-pin connector Black/Yellow wire. If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Black/Yellow wire between vent shut valve and fuse located in underdash fuse/relay box. See the WIRING DIAGRAMS article.
- Turn ignition off and reconnect vent shut valve 2-pin connector. Turn ignition on. Measure voltage between PCM 32-pin connector "A" terminal A10 (Black wire) and terminal A29 (Orange/Green wire). See Figure . If battery voltage does not exist, repair open in wire between vent shut valve and PCM connector terminal A29. See the WIRING DIAGRAMS article. If battery voltage exists, replace vent shut valve.
- Reconnect vacuum hose to EVAP 3-way valve. Disconnect EVAP purge control solenoid valve vacuum hose from EVAP canister (lower left hose). See Fig 1 . See the VACUUM DIAGRAMS article. Attach vacuum gauge to disconnected hose. Start 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. If vacuum exists, go to next step. If vacuum does not exist, go to step 9).
- Disconnect EVAP purge control solenoid valve 2-pin connector. Quickly increase engine speed to 3000 RPM and check for vacuum. If vacuum does not exist, go to next step. If vacuum exists, inspect vacuum hose routing. See the VACUUM DIAGRAMS article. If okay, replace EVAP purge control solenoid valve.
- Turn ignition off. Disconnect PCM 32-pin connector "A". See Figure . Check for continuity between ground and EVAP purge control solenoid valve connector Red/Yellow wire. If continuity exists, repair short in Red/Yellow wire between EVAP purge control solenoid valve connector and PCM connector "A" terminal A15 . See the WIRING DIAGRAMS article. If continuity does not exist, substitute a known-good PCM and recheck. If symptom or problem goes away, replace original PCM.
- Turn ignition off. Start engine and check for vacuum at EVAP purge control solenoid valve vacuum hose. Run engine at 3000 RPM with no loads and transmission in Park or Neutral, until radiator fan comes on. Allow engine to idle. Quickly increase engine speed to 3000 RPM and check for vacuum. If vacuum does not exist, go to next step. If vacuum exists, Go to step 13).
- Turn ignition off. Disconnect EVAP purge control solenoid valve 2-pin connector. Start engine. Measure voltage between EVAP purge control solenoid valve 2-pin connector terminals. If battery voltage does not exist, go to next step. If battery voltage exists, check vacuum hose routing. If vacuum is okay, replace EVAP purge control solenoid valve.
- Measure voltage between ground and EVAP purge control solenoid valve connector Black/Yellow. If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Yellow/Black wire or Black/Yellow wire between EVAP purge control solenoid valve connector and fuse No. 14 ECU (15-amp). See the WIRING DIAGRAMS article.
- Turn ignition off. Reconnect EVAP purge control solenoid valve 2-pin connector. Turn ignition on. Measure voltage between PCM 32-pin connector "A" terminal A10 (Black wire) and terminal A15 (Red/Yellow wire). See Figure . If battery voltage does not exist, repair open in Red/Yellow between EVAP purge control solenoid valve and PCM. See the WIRING DIAGRAMS article. If battery voltage exists, substitute a known-good PCM and recheck. If symptom or problem goes away, replace original PCM.
- Check EVAP 2-way valve. See EMISSION SYSTEMS & SUB SYSTEMS in the SYSTEM/COMPONENT TESTS article. Replace EVAP 2-way valve if faulty. If EVAP 2-way valve is okay, disconnect vacuum hoses from EVAP 2-way valve. Connect vacuum pump to EVAP 2-way valve (port to EVAP canister) and apply vacuum. See Fig 2 . If 2-way valve holds a vacuum, go to step 15). If 2-way valve does not hold a vacuum, go to next step.
- Disconnect EVAP by-pass solenoid valve 2-pin connector. Apply vacuum to hose. If 2-way valve holds a vacuum, repair short in wire between EVAP by-pass solenoid valve connector and PCM 32-pin connector "A" terminal A28. See the WIRING DIAGRAMS article. If 2-way valve does not hold a vacuum, replace EVAP by-pass solenoid valve.
- Turn ignition off. Connect a jumper wire between ground and PCM 32-pin connector "A" terminal A28. See Figure . Turn ignition on and apply vacuum to 2-way valve. If 2-way valve holds a vacuum, go to next step. If 2-way valve does not hold a vacuum, check following components for leakage to atmosphere, and repair or replace as necessary: fuel filler cap, fuel tank, fuel vapor pipe, EVAP 2-way valve, EVAP by-pass solenoid valve, fuel tank pressure sensor, EVAP control canister, EVAP control canister vent shut valve, EVAP purge control solenoid valve, and vacuum hoses and connections. See the VACUUM DIAGRAMS article.
- Turn ignition off. Disconnect EVAP by-pass solenoid valve 2-pin connector. Turn ignition on. Measure voltage between ground and EVAP by-pass solenoid valve connector Black/Yellow wire. If battery voltage exists, go to next step. If battery voltage does not exist, repair open in wire between EVAP by-pass solenoid valve connector and fuse No. 14 (15-amp) ECU. See the WIRING DIAGRAMS article.
- Turn ignition off. Reconnect EVAP by-pass solenoid valve 2-pin connector. Turn ignition on. Measure voltage between PCM 32-pin connector "A" terminal A10 (Black wire) and terminal A28 (Green/White wire). See Figure . If battery voltage exists, replace EVAP by-pass solenoid valve. If battery voltage does not exist, repair open in wire between EVAP solenoid valve connector and PCM connector A28. See the WIRING DIAGRAMS article.