What P0440 means
Evaporative Emission Control System Malfunction
Common causes (general)
Before spending money on parts, verify the code with a scan tool and read freeze frame data. Freeze frame captures every sensor value at the moment the code set — this is often enough to figure out the root cause without further testing.
Manufacturer-specific descriptions
Different manufacturers use this code for slightly different failure modes. Here's what your specific make means by P0440:
| AUDI | Missing fuel cap, Defective or damaged fuel cap, Distorted or damaged Fuel Tank Filler Neck, Torn or punctured Evaporative system hose(s), Defective Fuel Tank Sending Unit gasket or seal, Split or damaged Carbon Canister, Defective Evaporative Vent Valve and or Evaporative Purge Valve, Defective or damaged fuel tank |
| BMW | Evaporative Emission System |
| FORD | Evaporative Emission Control System Malfunction |
| MITSUBISHI | Evaporative Emission Control System Malfunction; EVAP.emission control system |
| NISSAN | Evaporative Emission Control System Malfunction |
| VOLKSWAGEN | Evaporative Emission (EVAP) System |
Read this code on your own car
DIY Fix My Car reads P0440 plus 25,000+ other DTC codes with manufacturer-specific descriptions. Includes freeze frame data, likely fix parts, and AI mechanic chat. Download free.