Evaporative Emission Control System Pressure Sensor Intermittent
Your car's evaporative emission control system has a pressure sensor that's dropping in and out of communication—like a faulty walkie-talkie that keeps cutting out. The ECU can't reliably read fuel tank pressure to detect fuel vapor leaks.
The ECU continuously monitors the EVAP pressure sensor voltage signal for continuity and valid range. When the sensor connection is loose or corroded, the signal becomes intermittent, triggering a fault code even if the sensor itself is functional. The ECM expects a steady analog voltage between 0.5–4.5V corresponding to tank pressure.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Sensor Voltage | 0.5–4.5 V (continuous signal) | Open/shorted circuit or signal dropout >2 seconds |
| Tank Pressure Reading | −10 to +10 inches H₂O | Erratic spikes or no signal detected |
Code P0455 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, P0455 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.