Evaporative Emission Control System Leak Detected
Your car's fuel vapor recovery system has a small leak that allows fuel fumes to escape instead of being recaptured. Think of it like a water bottle with a tiny crack—the seal isn't perfect, so some contents leak out.
The ECU monitors system pressure/vacuum using the fuel tank pressure sensor during the EVAP self-test cycle. It applies a small vacuum or pressure and checks if the system can hold it; a leak causes pressure decay faster than the threshold allows, triggering the code.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Fuel Tank Pressure Decay Rate | Holds 7-10 inches H2O for 30+ minutes | Loses pressure faster than 3-5 inches H2O per 30 minutes |
| EVAP System Integrity | Leak rate below 0.5 mm diameter equivalent | Leak rate above 0.5 mm diameter equivalent |
Code P0457 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, P0457 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.