EVAP Leak Detection Pump Sense Circuit High
The P2406 code indicates that the Engine Control Module (ECM) has detected a voltage signal from the evaporative emission (EVAP) leak detection pump sense circuit that is higher than the expected range. This circuit monitors the pump's operation during the EVAP system leak test. A high voltage reading typically points to a short to power, a faulty pump, or wiring issues. The EVAP system prevents fuel vapors from escaping into the atmosphere, so this fault can affect emissions and may trigger the check engine light.
1. Most Common Causes
- Faulty or internally damaged leak detection pump (LDP)
- Sense circuit wiring shorted to battery voltage (B+)
- LDP sensor ground circuit open or high resistance
- Corroded, loose, or damaged connector or pins at the LDP sensor
- Internal failure of the engine control module (ECM/PCM) monitoring the circuit
- Mechanical obstruction in the LDP preventing proper operation
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Possible failed emissions test
- No noticeable drivability issues in most cases
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve all codes and freeze frame data.
Step 2: Visually inspect the EVAP leak detection pump connector and wiring for damage, corrosion, or shorts.
Step 3: With key on engine off, measure voltage at the pump sense circuit; compare to manufacturer specifications.
Step 4: If voltage is high, disconnect the pump and recheck; if voltage drops, suspect pump internal short; if not, repair wiring short to power.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, it is generally safe to drive short distances, but the vehicle may fail an emissions test and the check engine light will remain on. It is recommended to diagnose and repair promptly to avoid potential EVAP system damage.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and repair, depending on labor rates and parts needed. If the pump requires replacement, parts can add $50-$100.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.