Conditions for Running the DTC

WARNING: This page is about a different car, the 2009 Pontiac Torrent and 2009 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.

P0450

DTC P0100, P0101, P0102, P0103, P0116, P0117, P0118, P0119, P0443, P0449, P0458, P0459, P0498, P0499, P050A, P0506, P0507, P0700, P2227, P2228, or P2229 is not set.
The engine is operating.
The ambient air temperature is greater than -7°C (+19°F).
The vehicle speed is less than 31 km/h (19 mph).
The ECM has commanded the EVAP canister vent valve open for greater than 3 seconds, 4 seconds for LLT.
DTC P0450 runs continuously once the above conditions are met for approximately 25 seconds.

P0451 Condition 1

DTC P0100, P0101, P0102, P0103, P0116, P0117, P0118, P0119, P0443, P0449, P0458, P0459, P0498, P0499, P050A, P0506, P0507, P0700, P2227, P2228, or P2229 is not set.
The engine is operating for greater than 1 second.
The engine is idling.
The ambient air temperature is greater than -7°C (+19°F).
The vehicle speed is less than 10 km/h (6 mph) for greater than 29 seconds.
The BARO is greater than 68 kPa.
The fuel level is between 11-88 percent.
The ECM has commanded the EVAP canister purge solenoid ON.
The ECM has commanded the EVAP canister vent valve closed for greater than 4 seconds.
DTC P0451 runs continuously when the above conditions are met for approximately 26 seconds.

P0451 Condition 2

DTC P0100, P0101, P0102, P0103, P0116, P0117, P0118, P0119, P0443, P0449, P0458, P0459, P0498, P0499, P050A, P0506, P0507, P0700, P2227, P2228, or P2229 is not set.
The engine is operating.
The BARO is greater than 68 kPa.
The fuel level is between 11-88 percent.
The ECM has commanded the EVAP canister purge solenoid OFF.
The ECM has commanded the EVAP canister vent valve open.
OR
The fuel level is less than 60 percent, 73 percent for LLT.
The vehicle speed is between 10-76 km/h (6-47 mph) fro greater than 30 seconds.
The ECM has commanded the EVAP canister purge solenoid ON.
OR
The calculated ambient air temperature is between 4-35°C (39-95°F) for greater than 3 seconds.
DTC P0451 runs continuously when the above conditions are met for approximately 7 seconds.