Unable To Bleed - Up Vacuum in Tank
Your car's fuel tank can't properly balance its air pressure, like a sealed bottle that can't breathe when you try to pour liquid into it. The evaporative emissions system is failing to release vacuum buildup from the tank.
The ECU monitors the fuel tank pressure sensor to verify the evaporative purge system can release vacuum during refueling. When the tank cannot bleed up (equalize pressure), the sensor detects abnormal vacuum levels that persist beyond expected thresholds. The ECM sets this fault when pressure regulation fails during the diagnostic purge test cycle.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Fuel Tank Pressure | -7 to +10 inches H2O | Excessive negative pressure exceeding -10 inches H2O |
| Purge Valve Response Time | Pressure equalizes within 30 seconds | Pressure fails to equalize after 60+ seconds |
Code P1457 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, P1457 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.