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P2406 OBD-II Trouble Code: Evaporative Emission System Leak Detection Pump Sense Circuit High

Check Engine Light

P2406 code definition

EVAP Leak Detection Pump Sense Circuit High

What the P2406 code means

P2406 is an OBD-II code that signals the engine control module (ECM) has detected a malfunction with the EVAP leak detection pump sense circuit and is getting a high voltage return indicating a short to power in the sensor or circuit.

What causes the P2406 code?

  • The ECM has detected a short in the circuit of the EVAP pump sense circuit.

  • The cause of code P2406 can be a leak detection pump short circuit or the connector corroded causing shorted contacts in the connector.

  • The code can also be set if the wiring to the valve is damaged between the ECM and the pump sense circuit.

What are the symptoms of the P2406 code?

  • The Check Engine Light will be illuminated and the code is set in ECM memory.

  • You may notice a slight drop in fuel mileage if the vapor system is not working or has a leak to atmosphere.

  • You may smell gasoline fumes if there is a fuel vapor leak that cannot be detected due to this failure.

How does a mechanic diagnose the P2406 code?

  • Scans codes and documents the code in the ECM. Views the freeze frame data to see when the fault happened

  • Inspects the entire EVAP wiring and system to include the pump connector for corrosion, damage, or loose connection or wires

  • Checks pump sense circuit for shorts in the circuit following pinpoint tests

  • Checks the EVAP pump for proper resistance of the pump and then checks operation of the pump using the ECM to control the pump to see if the pump or pump sense circuit is causing the failure

Common mistakes when diagnosing the P2406 code?

  • Assuming the EVAP pump is defective without doing a thorough diagnostic of the complete system to later find the wiring is shorted

  • Failing to verify the failure and replacing parts that may or may not be the problem

  • Not confirming repair is complete and then clearing codes

How serious is the P2406 code?

  • Code P2406 causes the Check Engine Light to go on and this alone will cause a failed emission test. The EVAP leak pump may not run a system check after the engine is off and will fail the emission monitors.

What repairs can fix the P2406 code?

  • Testing and replacing the EVAP leak pump

  • Repairing the damaged wiring to the EVAP leak detection pump and securing the harness from getting damaged again

  • Clearing codes and verifying operation of the EVAP system

Additional comments for consideration regarding the P2406 code

Code P2406 is a failure of the EVAP system leak detection pump that in most cases will only run after the engine is shut off and has had a time delay set in the computer for a run of the pump. Running the test manually can be done using a scanner to actuate the pump and checking the sense circuit before and after the repairs have been made.

Need help with a P2406 code?

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The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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