Fault code P240A – evaporative emission system leak detection pump heater control circuit/open

Fault code P240A is called “Evaporative Emission (EVAP) System Leak Detection Pump Heater 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 P240A

This Diagnostic Trouble Code (DTC) is a generic code. Error P240A 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 P240A – evaporative emission system leak detection pump heater control circuit/open

The 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, 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, due to the vacuum created by engine operation, allows fuel vapors to be drawn in. They flow from the fuel tank into the engine for combustion, rather than escaping into the atmosphere.

In some EVAP systems, an electronic leak detection pump is used to pressurize the system. Therefore, the system can be checked for leaks or flow.

Leak detection reference holes can be placed either at one point or at multiple points throughout the EVAP system. Leak detection holes are usually linear so that flow can be accurately measured when the pump is activated.

The PCM uses the input signals from the EVAP pressure and flow sensors in conjunction with the reference orifice to determine if the system is working properly.

The EVAP leak detection reference orifice is usually small, with a filter or just a section of the EVAP line. It restricts the flow so that the EVAP pressure or flow sensor can get an accurate sample.

If the PCM detects an open circuit in the fuel vapor leak detection pump heater control, code P240A will be stored. The Malfunction Indicator Light (MIL) may also illuminate.

Symptoms of vehicle malfunctions

The main signal that an error P240A 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 memory as a fault).
  2. There may be a smell of fuel in some cases.
  3. Slight decrease in engine performance.
  4. A slight increase in fuel consumption.
  5. In most cases, you will not notice any symptoms other than a lit control lamp (MIL).

The severity of fault code P240A is medium. The vehicle will be able to keep going, but the emissions will increase. In practice, it will not be able to pass the emissions test.

Factors that can cause this error code

The error code P240A can mean that one or more of the following problems have occurred:

  • Defective leak detection pump heater.
  • Corroded, broken or shorted system circuits or connectors.
  • Defective EVAP pressure sensor.
  • Damaged EVAP line.
  • Incorrectly installed fuel tank cap.
  • Carbon canister is damaged or clogged.
  • Defective vent or purge control solenoid.
  • Sometimes faulty PCM module is the cause.

How to fix or reset OBD-2 code P240A

Some suggested steps for troubleshooting and fix the error code P240A:

  1. Check leak detection pump heater.
  2. Test electrical circuits and connectors, and repair if necessary.
  3. Inspect for damaged EVAP lines.
  4. Check EVAP pressure sensor.
  5. Inspect the EVAP lines as well as the carbon canister.
  6. Replace the PCM if the situation requires it.

Diagnose and repair of problems

When starting to correct error P240A, make sure 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.

Check 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 may cause this fault code to activate.

Visual inspection

Because code P240A is a general fault code, it can often be associated with damaged or corroded wiring. Also with a faulty sensor or leak detection pump.

Locate the EVAP canister under the vehicle. It may be attached to the fuel tank or be separated from it by the hoses going to the fuel pump. Make sure that the EVAP control pressure sensor connector is fully inserted and locked in place.

Inspect the connector for corrosion, disconnect the sensor and inspect the terminal pins. To make sure they are clean and free of moisture. Inspect the wiring from the sensor to determine if there are any tears, blows on the wire insulation. Which may indicate corrosion inside the wire.

Check the voltage on the sensor and pump

Make sure there is 5 volts on the control wire, and check that the ground circuit is intact. Check the signal wire with a multimeter to determine the voltage, it should be about 3 volts.

Remove the hose attached to the EVAP pressure sensor and pump and create a vacuum with a vacuum gauge, monitoring the voltage changes on the multimeter. If the voltage changes when the vacuum is applied, everything is working. If the voltage does not change, then there is a malfunction.

Perform a wiggle test to determine if there is a problem. By jiggling or wriggling the wires, watch the readings on the multimeter to see if there are voltage fluctuations. If the voltage rises or drops sharply when you turn a section of wire, you probably have a break that needs to be repaired.

In the event that the poke test fails, disconnect the EVAP pump and check the voltage. If the voltage remains high with the pump disconnected, check the wiring harness for a shorted signal wire.

If the reference voltage and ground readings are good, a faulty EVAP pump is most likely the problem. Therefore, it will have to be replaced to correct error P240A.

There are times when the pump is turned off, the high voltage disappears, the ground circuit is good, and the reference voltage is correct. This is an indication that the EVAP purge hose is clogged. Disconnect the hose from the purge valve and blow it out with compressed air. If the clog cannot be cleared, replace the hose.

On which vehicles does this problem occur most frequently

Fault code P240A 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 (X5)
  • Mercedes-Benz
  • Volkswagen (Jetta)

Fault code P240A can sometimes be found with other errors. The most common are the following: P240B, P240C.

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