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 voltage reading suggests a short to ground, open circuit, or a faulty pump assembly, which can prevent the EVAP system from completing its self-test, potentially causing increased emissions.
1. Most Common Causes
- Faulty EVAP leak detection pump heater (internal open circuit)
- Damaged, corroded, or shorted-to-ground wiring or connectors in the heater control circuit
- Blown fuse in the heater power supply circuit
- Faulty PCM/ECM (internal driver damaged)
- Poor ground connection at the pump or module
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Failed EVAP system monitor test
- Possible fuel odor near the vehicle
- Rough idle or hesitation (rare)
3. 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: Measure resistance across the pump heater terminals; compare to manufacturer specs (typically 2-10 ohms).
Step 4: Check for battery voltage at the pump heater power wire with key on; if no voltage, inspect fuses and relay.
Step 5: Verify ground continuity at the pump; repair any open or short circuits as needed.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, it is generally safe to drive, but the Check Engine Light will remain on and the vehicle may fail an emissions test. The EVAP system will not function properly, potentially allowing fuel vapors to escape.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on whether the pump assembly needs replacement or just a wiring repair.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.