Knocking Noise That Repeats Three Times on Cold Start (Install New EVAP Canister V ent Solenoid Valve)

Important: The noise emitted from the evaporative emissions vent solenoid is not indicative of any condition with the solenoid or the customer's vehicle. Please inform your customer that the sound heard is the result of the valve cycling during a required emissions test. If the knowledge that the vehicle is operating properly relieves the customer concern, DO NOT replace the EVAP solenoid. If the customer expresses that the noise is offensive, replace the EVAP solenoid with a newly available and quieter operating solenoid using the procedure in this bulletin.

Some customers may comment on a knocking noise heard from the rear area of the vehicle. The knocking noise occurs three times after a cold start up and usually while driving the vehicle under 16 km/h (10 mph).

The EVAP emission system performs a series of tests upon cold start up to ensure that the EVAP system is operating normally. The EVAP canister vent solenoid valve will purge and cycle the solenoid causing a noise that might be heard inside the vehicle and perceived as a knocking noise.

Replace the EVAP canister vent solenoid valve with a quieter updated EVAP canister vent solenoid valve following the procedure below:

1. Raise and suitably support the vehicle.
2. Disconnect the chassis EVAP pipe quick connect fitting (1) from the EVAP canister.
3. Disconnect the fuel tank vapor line quick connect fitting (3) from the EVAP canister.
4. Disconnect the fuel fill pipe vent line quick connect fitting (2) from the EVAP canister.
5. Remove the three EVAP canister nuts.
6. Lower the EVAP canister until the EVAP canister vent solenoid valve can be disconnected.
7. Disconnect the rear body harness electrical connector from the EVAP canister vent solenoid valve.
8. Remove the EVAP canister.
9. Place the EVAP canister on a suitable work surface.
10. Rotate the EVAP canister vent solenoid valve counterclockwise to remove the EVAP canister vent solenoid valve.
11. Install the EVAP canister vent solenoid valve to the canister.
12. Rotate the EVAP canister vent solenoid valve clockwise until the solenoid valve comes to a stop in the retainer.
13. Place the EVAP canister near the body and connect electrical connector to the EVAP canister vent solenoid valve.
14. Install EVAP canister onto the studs.
15. Install the three EVAP canister nuts.

Tighten
Tighten the EVAP canister nuts to 6 N·m(53 lb in).

16. Connect the fuel fill pipe vent line quick connect fitting (2) to the EVAP canister.
17. Connect the fuel tank vapor line quick connect fitting (3) to the EVAP canister.
18. Connect the chassis EVAP pipe quick connect fitting (1) to the EVAP canister.
19. Lower the vehicle.

For vehicles repaired under warranty, use: