Evaporative Emission System Leak Detection Pump Heater Control Circuit High
Diagnostic trouble code P240C indicates that the powertrain control module (PCM) has detected a high voltage condition in the control circuit for the evaporative emission (EVAP) system leak detection pump heater. This typically means the circuit is shorted to voltage or has an open circuit that the PCM interprets as a high voltage state.
This code primarily affects the vehicle's emissions system and will not cause drivability issues. It is safe to drive, but should be repaired to ensure the EVAP system functions correctly and to pass emissions testing.
Common symptoms
- Illuminated Check Engine Light (MIL)
- Failed emissions test
- No noticeable drivability symptoms
- Possible slight decrease in fuel economy
- EVAP system monitor will not run to completion
Likely causes
- Faulty EVAP leak detection pump heater
- Short to voltage in the leak detection pump heater control circuit
- Open circuit in the leak detection pump heater wiring harness
- Corroded or damaged connector at the leak detection pump
- Faulty Powertrain Control Module (PCM) (rare)
What to check before replacing parts
Scan for other EVAP codes and clear the code to see if it returns.
Look for: If the code returns immediately, it indicates a hard fault in the circuit rather than an intermittent issue.
Visually inspect the wiring harness and connector at the EVAP leak detection pump.
Look for: Look for chafed wires, melted insulation, or corroded pins that could cause an open circuit or short to voltage.
Test the leak detection pump heater control circuit for voltage with a multimeter.
Look for: With the key on and the heater commanded off, check for unexpected battery voltage on the control wire, which indicates a short to voltage.
Measure the resistance of the EVAP leak detection pump heater element.
Look for: Compare the resistance reading to the manufacturer's specification. An infinite reading (OL) indicates an open internal heater element.
Check the ground circuit for the leak detection pump heater.
Look for: Ensure there is a solid ground connection with low resistance (typically less than 1 ohm) to the chassis or PCM.
This page explains the generic P240C definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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