Diagnostic Aids

WARNING: This page is about a different car, the 2007 GMC Sierra, 2007 GMC Cab & Chassis Sierra, 2007 Chevrolet Silverado, and 2007 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Ensure that the reference port on the FTP sensor is unobstructed.
Scan tool output controls, snapshot, and the plot function can help detect erratic sensor operation. To observe the Fuel Tank Pressure Sensor signal under vacuum conditions, use the Quick Snapshot and the EVAP Purge/Seal function to capture data while commanding purge to 20 percent. Then plot the data to look for erratic sensor operation. A similar test can be done for the pressure side of the sensor range by applying pressure with J 41413-200 while taking a snapshot with the scan tool.