P2403 - Evaporative Emission System Leak Detection Pump Sense Circuit Open
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System
Powertrain (Engine & Gearbox)
OBS!This code is in a manufacturer-specific range. The description may vary depending on the vehicle manufacturer.
Related Fault Codes
Evaporative Emission (EVAP) Leak Detection Pump Control Circuit/Open
Evaporative Emission System Leak Detection Pump Control Circuit Low
Evaporative Emission System Leak Detection Pump Control Circuit High
Evaporative Emission (EVAP) Leak Detection Pump Sense Circuit Range/Performance
Technical Description
The P2403 code is triggered when the Engine Control Module (ECM) detects an open circuit in the signal or control line of the Evaporative Emission (EVAP) system's Leak Detection Pump (LDP). This pump is responsible for pressurizing or creating a vacuum in the fuel system to verify its integrity against hydrocarbon leaks. The ECM monitors the circuit's electrical load and voltage. If it detects that the circuit is open (discontinuity), the diagnostic monitor fails. While this doesn't directly affect engine driveability, it disables the emissions monitoring for evaporative leaks, leading to higher environmental impact.
Possible Causes
Open circuit or corrosion in the Leak Detection Pump connector (typically located near the rear axle)
Failing Leak Detection Pump (internal open circuit in pump windings)
Damaged wiring harness between ECM and pump (rodent damage or chafing)
Faulty Engine Control Module (ECM)
Symptoms
Recommended Solution
- STEP 1: Visually inspect the connector at the Leak Detection Pump (usually located near the rear wheel well or fuel tank). Check for corroded pins or loose wiring.
- STEP 2: Measure the resistance (Ohm) across the pump terminals. A typical value is between 10-30 Ohms depending on the OEM spec. Infinite resistance indicates an internal open circuit.
- STEP 3: Verify power and ground. With ignition ON, the pump should have 12V supply. Check for continuity on the signal wire back to the ECM pin.
- STEP 4: If an internal open circuit is confirmed in the pump, replace the LDP and clear the DTC.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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