EVAP Leak Detection Pump Heater Control Circuit Low
The P240B code indicates that the powertrain control module (PCM) has detected a low voltage condition in the heater control circuit of the evaporative emission (EVAP) leak detection pump. This pump is part of the EVAP system, which prevents fuel vapors from escaping into the atmosphere. The heater element is used to warm the pump during cold starts to ensure proper operation. A low circuit condition typically means the voltage is below the expected threshold, often due to a faulty pump, wiring issues, or a blown fuse.
01. Most Common Causes
- Faulty EVAP leak detection pump assembly
- Open or shorted heater control circuit wiring
- Blown fuse or bad relay for the pump heater
- Corroded or loose electrical connector at the pump
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Failed emissions test due to EVAP system fault
- Possible fuel odor near the vehicle
- No noticeable drivability issues in most cases
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve all codes and freeze frame data.
Step 2: Inspect the EVAP leak detection pump connector for corrosion, damage, or loose pins.
Step 3: Check the heater circuit fuse and relay; replace if blown.
Step 4: Measure voltage at the pump heater connector with key on; should be battery voltage. If low, trace wiring for shorts or opens.
Step 5: If voltage is correct, test the pump heater resistance (typically 2-10 ohms); replace pump if out of spec.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, it is generally safe to drive, but the check engine light will stay on and the vehicle may fail an emissions test. The EVAP system leak detection may be impaired, but drivability is usually unaffected.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on whether the pump needs replacement or just a wiring repair. The pump itself costs around $30-$80.