DTC P1456 & P1457 - EVAP System Leak Detected
- If either DTC P1456 or DTC P1457 sets, check for:
- A faulty fuel filler cap.
- Proper vacuum hose 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.
- Faulty throttle body.
Repair as necessary. If no problems are found, go to next step.
- Disconnect vacuum hose from EVAP 3-way valve and connect vacuum pump to hose. See Fig 1 . See VACUUM DIAGRAMS article. Remove EVAP control canister vent shut valve from top of canister. 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 (Light Green/White wire). See Figure . See 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 terminal No. 2 (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 No. 15 ALTERNATOR SP SENSOR (7.5-amp) fuse located in underdash fuse/relay box. See WIRING DIAGRAMS article.
- Turn ignition off. Reconnect vent shut valve 2-pin connector. Turn ignition on. Using backprobe kit, measure voltage between PCM 32-pin connector "A" terminal A10 (Black wire) and terminal A29 (Light Green/White wire). See Figure . If battery voltage does not exist, repair open in Light Green/White wire between vent shut valve and PCM connector. See WIRING DIAGRAMS article. If battery voltage exists, replace EVAP control canister vent shut valve.
- Reconnect vacuum hose to EVAP 3-way valve. Disconnect EVAP purge control solenoid valve vacuum hose from EVAP canister (upper left hose). See Fig 1 . See VACUUM DIAGRAMS article. Attach vacuum gauge to disconnected hose. Start engine and allow it to idle. Ensure engine coolant temperature is less than 154°F (68°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 VACUUM DIAGRAMS article. If vacuum hose routing is 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 2-pin harness connector terminal No. 2 (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 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. Set parking brake and block rear wheels. Raise and support front suspension with wheels off the ground. Start engine and run at 3000 RPM with no loads and transmission in Park or Neutral until radiator fan comes on. Allow engine to idle. Check for vacuum at EVAP purge control solenoid valve vacuum hose with A/T in "2" position or M/T in 1st gear. Carefully increase engine speed quickly 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 and allow it to idle at normal operating temperature. Measure voltage between EVAP purge control solenoid valve 2-pin harness 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 2-pin harness connector terminal No. 1 (Black/Yellow wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Black/Yellow wire between EVAP purge control solenoid valve connector and No. 15 ALTERNATOR SP SENSOR (7.5 amp) fuse. See WIRING DIAGRAMS article.
- Turn ignition off. Reconnect EVAP purge control solenoid valve 2-pin connector. Turn ignition on. Using backprobe kit, 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 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 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 Blue wire between EVAP by-pass solenoid valve connector and PCM 32-pin connector "A" terminal A28. See WIRING DIAGRAMS article. If 2-way valve does not hold a vacuum, replace EVAP by-pass solenoid valve.
- Turn ignition off. Connect a fused jumper wire between ground and PCM 32-pin connector "A" terminal A28 (Blue wire). 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 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 2-pin connector terminal No. 1 (Black/White 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 No. 15 (7.5 amp) ALTERNATOR SP SENSOR fuse. See WIRING DIAGRAMS article.
- Turn ignition off. Reconnect EVAP by-pass solenoid valve 2-pin connector. Turn ignition on. Using backprobe kit, measure voltage between PCM 32-pin connector "A" terminal A10 (Black wire) and terminal A28 (Blue wire). See Figure . If battery voltage exists, replace EVAP by-pass solenoid valve. If battery voltage does not exist, repair open in Blue wire between EVAP solenoid valve connector and PCM connector A28. See WIRING DIAGRAMS article.