P0440 Code: Evaporative Emission Control System Malfunction
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Qu'est-ce que cela signifie ?
Code P0440 indicates a general malfunction in the EVAP system, which prevents fuel vapors from escaping into the atmosphere. The PCM detected a problem during an EVAP system test.
Diagnostic system: EVAP leak and purge system
On a Nissan Leaf, the P0440 code should be diagnosed as part of the evap leak and purge system group. Related codes and live data from this same system can change the repair priority, so avoid replacing parts from the code name alone.
Most Common Causes for Nissan Leaf
- Bouchon de réservoir desserré, endommagé ou manquant
- Vanne de purge EVAP défectueuse
- Électrovanne de mise à l'air EVAP défectueuse
- Tuyau EVAP fissuré ou déconnecté
- Canister EVAP saturé ou endommagé
Symptômes à surveiller
- Le voyant moteur est allumé
- Forte odeur de carburant du véhicule
- Échec au contrôle des émissions
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- Confirm the fuel cap seals correctly and is the right type for the vehicle.
- Inspect EVAP hoses, purge valve, vent valve, and charcoal canister connections.
- Use a smoke test before replacing multiple EVAP parts.
- Check for blown fuses, weak battery voltage, and damaged connectors before buying major parts.
Comment Diagnostiquer
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Replacing the gas cap repeatedly without smoke-testing the EVAP system or checking purge and vent valve operation. Always confirm the fault with freeze-frame data, live data, visual inspection, and circuit checks before spending money on parts.
CodePage.faq
Can I drive with the P0440 code?
If the check engine light is solid, you can usually drive to a safe location or mechanic. If the light is flashing, pull over immediately to prevent catastrophic engine or catalytic converter damage.
Will the P0440 code clear itself?
Once the underlying problem is fixed, the engine computer will run its self-checks. If it passes over several drive cycles, the light will turn off automatically. You can also clear it immediately using an OBD2 scanner.
Will this code fail an emissions test?
Yes. If the Check Engine Light is on due to the P0440 code, your Nissan will automatically fail an OBD2 plug-in emissions or smog test.
What should I check first for P0440?
Confirm the fuel cap seals correctly and is the right type for the vehicle. Inspect EVAP hoses, purge valve, vent valve, and charcoal canister connections. Use a smoke test before replacing multiple EVAP parts.
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Estimation de réparation
Fuel cap, hose clamp, or small EVAP hose repair
Major component replacement after live data and circuit tests confirm failure
Comprend les pièces et la main-d'œuvre. Peut varier selon l'emplacement.
Many EVAP fixes are low to moderate cost, but smoke testing saves money by locating the exact leak.
Difficulté de réparation (DIY)
Can usually be performed at home with basic hand tools.