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P2409 OBD-II Trouble Code: Fuel Cap Sensor/Switch Circuit Range/Performance

Check Engine Light

P2409 code definition

Fuel Cap Sensor/Switch Circuit Range/Performance

What the P2409 code means

P2409 is an OBD-II generic code for the Engine Control module (ECM) detecting the fuel cap sensor, switch or circuit is out of range or performance within the specifications.

What causes the P2409 code?

  • The ECM monitors the fuel cap to see if it is open or closed. The code is set when the fuel cap is left open or the circuit has failed open.

  • The Evaporative Emission Control System (EVAP) cannot operate correctly if the fuel cap is left open.

  • The fuel cap sensor is out of the specified range for a closed or open cap.

What are the symptoms of the P2409 code?

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

  • The vehicle will not run any different in most cases.

  • The vehicle may have a fuel odor in the vehicle or around the fuel cap.

  • The vehicle may have a Check Gas Cap Light on in the dash.

  • The vehicle will fail emission testing.

How does a mechanic diagnose the P2409 code?

  • Try to scan for codes and document the codes in the ECM memory and look at the freeze frame data for the problem before clearing the codes and retesting.

  • Check the fuel cap to see if it is loose or missing.

  • Test the resistance of the cap switch or sensor and check toward its specification.

  • Test wiring for open circuits between the ECM and the cap sensor.

Common mistakes when diagnosing the P2409 code?

  • Clearing ECM memory codes before checking the freeze frame data for the main failure problem, so the failure may be duplicated and repaired.

  • Failing to clear the ECM codes after the codes are fixed.

  • Failing to verify the failure before replacing parts.

  • Failing to check with the vehicle operator to see if the cap was recently left off or loose.

How serious is the P2409 code?

Code P2409 is an indication that the gas cap is not closed or not activating the cap closed switch or sensor. The cap being left off can cause fumes to build up around the vehicle. Dirt and water may be able to get in the tank and contaminate the fuel in the tank if the cap is off.

What repairs can fix the P2409 code?

  • Replace the gas cap if it is not closing properly or is missing.
  • Replace the gas cap closed sensor or switch.
  • Repair the wiring to the gas cap switch or sensor.

Additional comments for consideration regarding the P2409 code

Code P2409 is for the gas cap closed sensor or switch. The most common cause for this code is when the operator is not closing the cap tight enough every time and the sensor detects this as a performance problem with the sensor, thus turning on the light and setting the code.

Need help with a P2409 code?

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