Knocking Noise that Repeats Three Times on Cold Start (Replace EVAP Canister Vent Solenoid Valve)

This bulletin is being revised to update the information and change the part number for the EVAP Canister Vent Solenoid Valve. Please discard Corporate Bulletin Number 06-06-04-062 (Section 06 -- Engine/Propulsion System).

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. Refer to Evaporative Emission Canister Vent Solenoid Valve Replacement in SI.

For vehicles repaired under warranty, use: