Error code

OBD2 P0440

OBD2P0440
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

Evaporative Emission System.

Severity

moderateYou can usually drive the vehicle, but it's best to address the issue soon.

Summary

P0440 indicates an issue with the evaporative emission control system (EVAP) that prevents it from sealing properly or holding vacuum.

Symptoms

  • Check Engine Light is on
  • Reduced fuel economy

Common Causes

  • Loose, missing, damaged, worn, or incorrect gas cap
  • Stuck EVAP canister close valve or purge valve
  • Damaged charcoal canister or associated tubes and hoses
  • Previous repairs that may have disconnected EVAP components improperly

Diagnosis

  1. Check and tighten gas cap properly
  2. Inspect charcoal canister for damage or saturation
  3. Look for cracks or disconnections in EVAP hoses and tubes
  4. Test valves with a power source to ensure they are not stuck open

Fixes

  • Replace damaged gas cap, charcoal canister, or faulty valves

FAQ

How long does it take for the code to reset after fixing P0440?

It may take up to 40 drive cycles for the code to clear automatically, or you can use a scan tool to clear it immediately.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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