Fault code P0447 – evaporative emission control system vent control circuit open

Fault code P0447 is called “Evaporative Emission (EVAP) Control System Vent Control Circuit Open” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0447

This diagnostic trouble code (DTC) is a generic code. Error P0447 is considered a generic code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.

Fault code P0447 – evaporative emission control system vent control circuit open

The code indicates that an open circuit has occurred in the EVAP system control circuit. The EVAP system consists of many parts, including (but not limited to) the tank cap, fuel lines, carbon tank, air valve, and others.

The emission control system (EVAP) prevents fuel vapor from escaping from the vehicle’s fuel system. Fuel vapors are routed through hoses to a carbon canister for storage. Later, when the engine is running, the purge control valve opens, allowing fuel vapors to be drawn in under vacuum.

The EVAP canister purge is controlled by a valve that allows fuel vapors to be drawn in due to the vacuum created by engine operation. These flow from the fuel tank into the engine for combustion, rather than escaping into the atmosphere.

If the ECM controller detects an open circuit in the control circuit, fault code P0447 is set. The malfunction indicator lamp (MIL) is also activated.

Symptoms of vehicle malfunctions

The main signal that an error P0447 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” control lamp on the control panel will light up (the code will be written in the ECM memory as a malfunction).
  2. If the EVAP vent valve is stuck in the open position, you may smell fuel.
  3. A slight decrease in engine performance.
  4. A slight increase in fuel consumption.
  5. In most cases, you won’t notice any symptoms other than a lit control lamp (MIL).

The severity level of code P0447 is medium. The car will be able to continue driving, but the harmful emissions will increase. Which, in practice, will not allow the vehicle to pass the emission test.

Factors that can cause this error code

The error code P0447 can mean that one or more of the following problems have occurred:

  • Internal short circuit or breakage of ventilation valve.
  • Break in wiring harness.
  • Shorted or broken connector.
  • Corrosion or resistance in connector.
  • Defective exhaust valve.
  • Open or shorted voltage supply circuit to exhaust valve.

How to fix or reset OBD-2 code P0447

Some suggested steps for troubleshooting and fix the error code P0447:

  1. Repair damaged EVAP lines.
  2. Repair open or shorted outlet valve voltage circuit.
  3. Repair circuit going to PCM.
  4. Replace exhaust valve.
  5. Repair or repair a restriction in the EVAP line.
  6. Repair or clean the connector.
  7. Replace PCM.

Diagnose and repair of problems

Check that all EVAP hoses are connected correctly and in good condition. Check wiring harnesses for obvious damage, due to fraying or improper routing. Inspect electrical connectors for corrosion, pins should be straight and properly installed.

Make sure that the tank lid gasket is in good condition and the lid is properly installed . Then clear code P0447 and test drive to see if the error returns again.

If the tank cap gasket is cracked, crushed, or otherwise damaged, replace it.

Make sure that the exhaust hose that carries fresh air into the canister is not blocked, clogged, or crushed. If insufficient air is drawn in during the purge cycle, it could set off this fault code.

Pressure check

Using a vacuum pump, disconnect the vent control valve from the charcoal cylinder. Attempt to create a vacuum on the valve. It should hold a vacuum for at least a minute without dropping. Use a 12 volt jumper to open the valve. The valve should open and immediately release all vacuum. Repeat this test for the purge control valve.

If the valve does not keep the vacuum closed or does not open when voltage is applied, replace the valve.

Electrical test

Check the resistance at the vent control valve. Most valve solenoids should have a resistance of 30 ohms to 40 ohms. But some newer electronically controlled valves may have a range of 2 ohms to 6 ohms.

If the resistance is 0 ohms or more than 10 kohms, replace the valve.

If the valve is functioning properly, and if it is electrically sound, check the rest of the circuit between the ECM controller and the valve. Look for corrosion or short circuits that may be preventing proper operation of the system.

When correcting a P0447 fault, you should clearly understand what you are doing. Otherwise, seek help from a specialist.

On which vehicles does this problem occur most frequently

Fault code P0447 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Chevrolet (Impala)
  • Hyundai (Accent, Elantra, Santa Fe)
  • Infiniti (G37, QX56)
  • Isuzu
  • Kia (Rio, Sorento)
  • Mercedes-Benz
  • Nissan (350Z, Altima, Frontier, Maxima, Murano, Pathfinder, Quest, Rogue, Sentra)
  • Subaru (Forester)

Fault code P0447 can sometimes be found with other errors. The most common are the following: P0038, P0138, P0170, P0183, P0440, P0441, P0442, P0443, P0444, P0445, P0446, P0448, P0449, P0450, P0452, P0453, P0455, P0456, P0501, C0305.


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