Code Error Location Probable Crusade
P0440 Evaporative emission (EVAP) organisation -malfunction
(Buy Function On Amazon)		 Hose connectedness(s), intake leak, EVAP canister purge valve

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What Does Code P0440 Mean?

In spite of the fact that fuel is delivered in liquid form, the internal combustion engine runs, not on liquid fuel, but on fuel vapors. This works out rather conveniently, since liquid fuel is far more easily manageable, only easily vaporizes into usable form, even when it's below zero. The tendency of fuel to vaporize, called volatility, makes for good engine starting, performance, and efficiency. At the aforementioned time, fuel volatility creates another problem, evaporative emissions. Fuel vapors are carcinogenic and environmentally destructive, which is why fuel storage, at the refueling station on in your vehicle, is designed to significantly reduce evaporative emissions.

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In your vehicle, the evaporative emissions control system, usually only referred to as the "EVAP" system, keeps fuel vapors from escaping into the atmosphere. Using a system of tubes and valves, the EVAP organisation routes fuel vapors from the fuel tank into an activated-charcoal canister for storage. At certain times, when the engine is running, the EVAP system will route fuel vapors from the canister to the engine, where they are burned. The ECM (engine control module) controls the EVAP organisation valves, monitoring system part via pressure sensors.

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Many of the self-tests that the ECM performs on the EVAP system require that certain conditions be met get-go, such as sufficient battery voltage, specific fuel level, and specific atmospheric temperature. Aside from circuit tests, one of the first things that the ECM needs to verify is that the fuel tank and the rest of the system is sealed. To run this test, the ECM draws a vacuum on the tank. If the ECM detects that the EVAP system is unable to produce or hold a vacuum in a certain amount of time, it records a diagnostic trouble code (DTC) in memory, P0440, "Evaporative Emissions (EVAP) Command Arrangement Malfunction," and illuminates the MIL (malfunction indicator lamp).

What are the common causes of code P0440 ?

Depending on yr, make, and model, DTC P0440 may have number of causes. Here are some of the most common.

  • Gas Cap – This is, by far, the well-nigh common failure. Loose, missing, damaged, worn, or incorrect gas caps will not seal the organization properly. Also, never refuel with the engine idling, as the ECM may elect to run the EVAP monitor at that time. Keep in listen that, if you lot tighten the gas cap afterwards the MIL comes on, it volition take 40 drive cycles for the ECM to clear the code on its own, unless you clear information technology with a scan tool.

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  • Stuck Valve – If the canister shut valve (CCV) or purge valve is stuck open, information technology volition not seal the organization. Depending on location, it can be contaminated or corroded, sticking open, even when not grounded by the ECM.
  • Canister Failure –
    • Because of its exposed position, the charcoal canister and associated tubes, hoses, and valves, are prone to harm.
    • Consistent "topping off the tank" has been known to saturate the charcoal canister with fuel, something which it was not designed for. Normally, the charcoal canister might weigh a couple of pounds, but a saturated canister might counterbalance up to 20 pounds.
    • An internally-ruptured canister, while external harm may be non-existent, may have immune charcoal pieces to arrive through to the engine intake, perhaps even sticking in the purge valve. Disconnect the EVAP purge line and await inside. If you lot meet charcoal dust or pellets, y'all may accept a ruptured canister.
  • Previous Repairs – If annihilation has been done on the vehicle, such as a tune-upward, engine rebuild, timing chugalug, or EVAP system repairs, EVAP hoses or connectors may accept been asunder and reconnected. Make sure all electric connectors, EVAP hoses, vacuum lines, and tubes are properly connected and sealed. Be wary of O-ring seals where plastic EVAP tubes connect to metal EVAP tubes.

What are the symptoms of lawmaking P0440 ?

Bated from the MIL, you will likely not notice any symptoms related to this EVAP system failure. Depending on the automaker'due south failure mode, you may notice reduced fuel economy or engine performance.

How exercise you lot troubleshoot code P0440 ?

Considering of the complication of the EVAP system and the expense and availability of EVAP-specific diagnostic tools, yous may be express to a visual inspection of the system. Because of the nature of this DTC, you're basically looking for anything that would prevent the system from sealing.

  • Other DTCs – P0440 oft appears with other EVAP-related DTCs, such as P0441, P0442, P0446, etc. If any other EVAP DTCs are present, diagnose and repair those first. After repairing whatsoever other faults in the system, you can then proceed to diagnosing DTC P0440.
  • Gas Cap – Brand sure the gas cap is installed properly and that it is an OE (original equipment) part. Bank check that the seal looks good, that is, smooth, flexible, no cracks or pitting. Brand certain the fuel filler neck, where the gas cap seals, is also smooth. Make sure the gas cap torques properly, that the clutch sounds even or that single-click types feel firm. Supersede as necessary. (At this bespeak, you tin can ordinarily clear the code and go on your mode.)

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  • Charcoal Canister – Inspect the charcoal canister for damage. Because of its exposed position on some vehicles, it may be damaged by road debris or dirt. Replace as necessary.
  • Tubes and Hoses – Similarly, make sure that all EVAP hoses and tubes appear intact and are continued properly. Cracked or disconnected hoses will not seal properly. Repair as necessary.
  • Valves – If possible, use a 12 V power source to bench-examination the purge valve and the canister close valve. With voltage applied, you should be able to easily blow air through the valve. With no voltage applied, no air should laissez passer through the valve. If the valve is corroded, damaged, or contaminated, it may stick open and will not seal the EVAP organization properly. Clean or replace as necessary.
  • Fuel Tank – Cheque the fuel tank and fuel filler tube for damage. Repair or supercede as necessary.
  • Pressure Testing – If yous accept access to the proper equipment, you can force per unit area examination the EVAP arrangement. Many vehicles have an EVAP test port under the hood, which you tin apply to pressurize the system, measure organisation force per unit area, and look for leaks. Keep in mind, however, that EVAP force per unit area testing should never go over 2 psi, otherwise y'all may harm the system. This should exist done with the fundamental off.
    • Disconnect or remove the purge valve. Air should not escape from the purge valve. Similarly, air should not escape from the canister close valve, which may be located under the hood or on or near the charcoal canister. Repair or replace equally necessary.
    • Prepare a spray canteen of soapy solution, fifty:50 dish detergent and h2o. Spray downwardly EVAP connections, hoses, canister, fuel tank, or any other suspected leak area. Bubbling will class if y'all find a leak. Repair every bit necessary.

If y'all cannot detect a problem, yous may need to have it to a professional for more in-depth diagnosis.

Codes Related to P0440

  • P0441 Evaporative Emission Control (EVAP) System Wrong Purge Menstruation
  • P0442 Evaporative Emission Command (EVAP) Organization Leak Detected (modest leak)
  • P0450 Evaporative Emission Control (EVAP) Arrangement Force per unit area Sensor
  • P0455 Evaporative Emission Control (EVAP) System Leak Detected (gross leak)
  • P0456 Evaporative Emission Command (EVAP) System Leak Detected (very small leak)
  • P0457 Evaporative Emission Control (EVAP) Organization Leak Detected (fuel cap loose/off)
  • P0496 Evaporative Emission Control (EVAP) System High Purge Flow
  • P0497 Evaporative Emission Control (EVAP) Organisation Low Purge Flow