2004-08 Aveo
2006-08 Cobalt, HHR
2007-08 G5
2005-06 Pursuit (Canada)
2005-08 Wave (Canada)
2006-07 ION
Shortly after cold starting the engine, three to five brief knock noises may be heard from the rear of vehicle. The sound resembles someone tapping on the rear window or quarter panel. This may be the result of the EVAP vent valve going through a normal diagnostic cleaning cycle.
If this concern is experienced and the noise is isolated to the EVAP vent valve, inspect the vent valve pipe to ensure that it is routed properly and not grounding out. If the pipe is routed properly, this noise should be considered a normal characteristic and no repairs should be performed.
- Thanks to Jamie Parkhurst
2006-08 Cobalt, HHR
2007-08 G5
2005-06 Pursuit (Canada)
2005-08 Wave (Canada)
2006-07 ION
Shortly after cold starting the engine, three to five brief knock noises may be heard from the rear of vehicle. The sound resembles someone tapping on the rear window or quarter panel. This may be the result of the EVAP vent valve going through a normal diagnostic cleaning cycle.
If this concern is experienced and the noise is isolated to the EVAP vent valve, inspect the vent valve pipe to ensure that it is routed properly and not grounding out. If the pipe is routed properly, this noise should be considered a normal characteristic and no repairs should be performed.
- Thanks to Jamie Parkhurst
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