Conditions for Setting the DTC

WARNING: This page is about a different car, the 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

The ECM detects that the FTP sensor voltage on a cold start-up is less than 0.3 volts or more than 2.95 volts for 25 seconds.
The ECM does not detect a change in tank vacuum when purge duty cycle is more than 40 percent. The change in vacuum must be less than 0.063 kPa (0.25 inches of H2O) when purge is active. This condition requires 3 failures to set the DTC for 10 seconds each time.
The ECM detects that the FTP sensor signal oscillates more than +/- 0.85 volts from a zero point for 25 seconds. For example, 1.5 volts = 0 pressure/vacuum change, the signal should not oscillate more than +/- 0.85 volts from this zero point. The zero point may vary between 1.0-2.5 volts. The vehicle speed must be less than 31 km/h (19 mph) for this test.