P1457

DTC P1457: EVAP Control System Leakage (EVAP Canister System)

NOTE: The fuel system is designed to allow specified maximum vacuum and pressure conditions. Do not deviate from the vacuum and pressure tests as indicated in these procedures. Excessive pressure/vacuum would damage the EVAP components or cause eventual fuel tank failure.

Special Tools Required
Vacuum pump/gauge, 0 - 30 in.Hg, Snap-on YA4000A or equivalent, commercially available

This is a two-trip code; once cleared, it cannot be reproduced in one trip. Also, certain specific driving and ambient conditions must occur before the ECM will complete the system checks. Additional test drives may still not meet the specific conditions needed to reproduce the code. If necessary, use the test drive procedures for setting the readiness code.

Follow these troubleshooting procedures carefully to ensure the integrity of the system and to confirm the cause of the problem or code.

NOTE:
- Fresh fuel has a higher volatility that will create greater pressure/vacuum. The optimum condition for testing is fresh fuel, at least half, but less than a full tank. If possible, to assist in leak detection, add 1 gallon of fresh fuel to the tank (as long as it will not fill the tank), just before starting these procedures.
- Before you troubleshoot, record all freeze data and review the general troubleshooting information.

EVAP Canister Purge Valve Test




1. Disconnect the vacuum hose from the EVAP purge joint (A), and connect a commercially available vacuum pump/gauge, 0 - 30 in.Hg, to the hose.




2. Turn the EVAP canister purge valve on with the HDS, or connect ECM connector terminal A6 to body ground with a jumper wire.
3. Turn the ignition switch ON (II).
4. Apply vacuum to the hose.

Does the valve hold vacuum?

YES - Go to step 5.

NO - The EVAP canister purge valve is OK. Go to step 10.

5. Turn the ignition switch OFF.
6. Disconnect the EVAP canister purge valve 2P connector.




7. Check for continuity between EVAP canister purge valve 2P connector terminal No. 2 and body ground.

Is there continuity?

YES - Go to step 8.

NO - Repair open in the wire between the EVAP canister purge valve and the ECM (A6).

8. Turn the ignition switch ON (II).




9. Measure voltage between EVAP canister purge valve 2P connector terminal No. 1 and body ground.

Is there battery voltage?

YES - Replace the EVAP canister purge valve.

NO - Repair open in the wire between the EVAP canister purge valve and the No. 6 ACG (15 A) fuse.

EVAP Bypass Solenoid Valve Test




10. Disconnect both vacuum hoses from the EVAP two way valve (A), and connect a commercially available vacuum pump/gauge, 0 - 30 in.Hg, to the canister port on the two way valve.
11. Turn the ignition switch ON (II).
12. Apply vacuum to the hose.

Does the valve hold vacuum?

YES - The EVAP bypass solenoid valve/EVAP two way valve is OK. Go to step 18.

NO - Go to step 13.

13. Turn the ignition switch OFF.
14. Disconnect the EVAP bypass solenoid valve 2P connector.







15. Check for continuity between EVAP bypass solenoid valve 2P connector terminal No. 2 and body ground.

Is there continuity?

YES - Go to step 16.

NO - Replace the EVAP bypass solenoid valve (A) and O-rings(B).

16. Disconnect ECM connector A (32P).




17. Check for continuity between EVAP bypass solenoid valve 2P connector terminal No. 2 and body ground.

Is there continuity?

YES - Repair the short in the wire between the EVAP bypass solenoid valve and the ECM (A3).

NO - Substitute a known-good ECM and recheck. If the symptom/indication goes away, replace the original ECM.

EVAP Canister Vent Shut Valve Test




18. Disconnect the vacuum hose from the EVAP canister vent filter line (A), and connect a commercially available vacuum pump/gauge, 0 - 30 in.Hg, to the hose.




19. Turn the EVAP canister vent shut valve on with the HDS, or connect ECM connector terminal A4 to body ground with a jumper wire.
20. Turn the ignition switch ON (II)
21. Apply vacuum to the hose.

Does the valve hold vacuum?

YES - The EVAP canister vent shut valve is OK. Go to step 27.

NO - Go to step 22.

22. Turn the ignition switch OFF.
23. Disconnect the EVAP canister vent shut valve 2P connector.




24. Check for continuity between EVAP canister vent shut valve 2P connector terminal No. 2 and body ground. If using the HDS to turn the EVAP canister vent shut valve on, turn the ignition switch ON (II).

Is there continuity?

YES - Go to step 25.

NO - Repair open in the wire between the EVAP canister vent shut valve and the ECM (A4).

25. Turn the ignition switch ON (II).




26. Measure voltage between EVAP canister vent shut valve 2P connector terminal No. 1 and body ground.

Is there battery voltage?

YES - Replace the EVAP canister vent shut valve (A) and the O-ring(B).

NO - Repair open in the wire between the EVAP canister vent shut valve and the No. 6ACG (15 A) fuse.

Canister System Leak Test

27. Turn the ignition switch OFF.




28. Connect two three-way T-fittings (A) into the hose from the EVAP canister to the EVAP two way valve. Connect the FTP sensor to one of the T-fittings and a commercially available vacuum pump/gauge, 0-30 in.Hg, to the other.




29. Remove the vent hose from the EVAP canister vent shut valve (A), and cap the port (B) to seal the fresh air vent for the EVAP canister.
30. Turn the ignition switch ON (II).
31. While monitoring FTP sensor voltage with the HDS, or measuring voltage between ECM connector terminals A29 and C18, slowly pump the vacuum pump.
32. Continue to pump vacuum until the voltage drops to about 1.5 V. Make sure that the engine coolant temperature is still above 95 degree F (35 degree C) and your vacuum pump has no leak.
33. Check the voltage for 20 seconds.

Does the voltage drop to 1.5 V and hold for at least 20 seconds?

YES - Inspect the EVAP canister vent shut valve line and connections.

NO - Go to step 34.

34. Turn the ignition switch OFF.




35. Disconnect the quick-connect fitting (A) from the EVAP canister, and plug the canister port (B).
36. Turn the ignition switch ON (II).




37. While monitoring FTP sensor voltage with the HDS, or measuring voltage between ECM connector terminals A29 and C18, slowly pump the vacuum pump.
38. Continue to pump vacuum until the voltage drops to about 1.5 V. Make sure the engine coolant temperature is still above 95 degree F (35 degree C) and your vacuum pump/gauge has no leak.
39. Monitor the voltage continuously for 20 seconds.

Does the voltage drop to 1.5 V and hold for at least 20 seconds?

YES - Inspect the fuel tank vapor control line and connections.

NO - Go to step 40.

40. Turn the ignition switch OFF.




41. Disconnect the purge line hose (A) from the canister at the metal line, and plug the hose (B).
42. Turn the ignition switch ON (II).
43. While monitoring FTP sensor voltage with the HDS, or measuring voltage between ECM connector terminals A29 and C18, slowly pump the vacuum pump/gauge.
44. Continue to pump vacuum until the voltage drops to about 1.5 V. Make sure that the engine coolant temperature is still above 95 degree F (35 degree C) and your vacuum pump/gauge has no leak.
45. Check the voltage for 20 seconds.

Does the voltage drop to 1.5 V and hold at least 20 seconds?

YES - Inspect the EVAP canister purge valve line and connections. If they are OK, test the EVAP two way valve, and the fuel tank vapor control valve.

NO - Replace the EVAP canister.