Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0440: EVAP System: Description
EVAP large leak test applies vacuum to Evaporative Emission (EVAP) system and monitors vacuum decay. PCM monitors the Fuel Tank Pressure (FTP) sensor signal to determine vacuum decay rate. At an appropriate time, PCM turns EVAP canister purge valve on (open) and EVAP vent valve on (closed). This allows engine to draw a vacuum on EVAP system. At a calibrated time, or vacuum level, PCM turns purge valve off (closed), sealing system, and monitors FTP sensor input in order to determine EVAP system vacuum. If system is unable to achieve calibrated vacuum level, or vacuum level decreases too rapidly, DTC P0440 will set.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.