Evaporative Emission (EVAP) System Flow During Non-Purge Oldsmobile Only
Your car's fuel vapor recovery system is leaking or allowing fuel vapors to escape when the engine isn't purging them. It's like a one-way valve that's stuck open, letting gas fumes escape when they should be trapped.
The ECM monitors the fuel tank pressure and flow through the EVAP canister vent valve during closed-loop operation. When flow is detected during non-purge periods, it signals a leak or stuck vent valve. The system expects zero or minimal airflow through the vent when the purge solenoid is closed.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Tank pressure during non-purge | -7 to -10 inches H2O | Unexpected pressure drop indicating flow through vent |
| Vent valve solenoid resistance | 25-35 ohms | Open or shorted coil |
Code P1446 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P1446 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.