Fault code P0440 is called “Evaporative Emission (EVAP) Control System Malfunction” 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 P0440
This Diagnostic Trouble Code (DTC) is a generic powertrain code. Error P0440 is considered a general code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.
This code indicates that part of the EVAP control system is no longer functioning properly. The EVAP system consists of many parts, including (but not limited to) the tank cap, fuel lines, carbon tank, purge 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.
A vacuum switch is used to detect the presence of flow. If the PCM gives a purge command and sees no response, code P0440 is set. Which indicates no purge flow detected.
Symptoms of vehicle malfunctions
The main signal that an error P0440 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.
It can also be warning signs such as:
- Activation of the Check engine indicator on the instrument panel.
- Possible perceptible smell of fuel caused by vapor emission.
A tightly closed fuel tank cap can sometimes be the cause of code P0440.
Factors that can cause this error code
The error code P0440 can mean that one or more of the following problems have occurred:
- Defective vacuum switch.
- Broken or damaged EVAP line or tank.
- Purge commands are not flowing through circuit to PCM.
- Open or short-circuited voltage supply circuit to purge solenoid valve.
- Defective purge solenoid.
- Restriction on EVAP solenoid, line, or tank.
- Corrosion or resistance in connector.
- Defective PCM.
How to fix or reset OBD-2 code P0440
Some suggested steps for troubleshooting and fix the error code P0440:
- General repair – replace leak detection pump / LDP.
- Repair damaged EVAP or tank lines.
- Repair open or shorted bleed solenoid voltage supply circuit.
- Repair circuit going to PCM.
- Replace purge solenoid valve.
- Replace vacuum breaker.
- Repair or repair restriction in Evap line, tank or solenoids.
- Repair or clean connector.
- Replace PCM.
Diagnose and repair of problems
The Engine Control Module (ECM) checks the EVAP system under the following conditions:
- Large and small leaks.
- Excessive vacuum.
- Purge flow under uncontrolled conditions.
- Faults in the fuel level and pressure sensor – EVAP.
- Fuel tank pressure sensor malfunctions.
- To determine the vacuum/pressure level in the EVAP system.
The ECM monitors the fuel tank pressure sensor. The ECM module instructs both the EVAP solenoid valve and the EVAP air valve to turn on. When the proper conditions are met to create a vacuum in the engine of the EVAP system.
The ECM orders the EVAP solenoid valve to turn off when the system reaches the specified vacuum level. This test verifies that the EVAP system vacuum can be reached.
Failure to reach vacuum may be caused by a large leak or flow restriction and as a consequence the P0440 fault appears.
On which vehicles does this problem occur most frequently
Fault code P0440 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
- BMW
- Chevrolet (Cavalier, Silverado)
- Chrysler (Pacifica, Sebring, Voyager)
- Citroen
- Daewoo (Leganza)
- Dodge (Caliber, Caravan, Intrepid, Neon, RAM, Stratus)
- Ford
- Hyundai (Elantra)
- Jeep
- Kia (Rio, Sportage)
- Lexus (LX470, RX300)
- Nissan (Sentra)
- Opel
- Peugeot (206)
- Pontiac (Vibe)
- Subaru
- Suzuki (Grand Vitara)
- Toyota (Camry, Celica, Corolla, Highlander, RAV4)
- Volkswagen (Golf)
- VAZ
Fault code P0440 can sometimes be found with other errors. The most common are the following: P0133, P0325, P0420, P0441, P0442, P0443, P0444, P0445, P0446, P0447, P0448, P0449, P0452, P0453, P0455, P0456, B1001, C0265, U1000.
