P2404: EVAP Leak Detection Pump Sense Circuit Range/Performance

What it means

The control module detects a sense signal from the EVAP leak detection pump that is outside the expected range or response. The code does not by itself identify a failed pump component.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

The leak detection pump's sense circuit sends feedback to the control module during EVAP leak testing. This code sets when the signal is present but its range or response does not match what the module expects, so it does not by itself prove the pump has failed.

Common causes

Most likely first.

1. Fault in pump sense circuit or connection
2. Leak detection pump fault
3. Wiring fault

Symptoms

• Check engine light on

How to diagnose it

1. Record freeze-frame data and compare the pump sense signal during an EVAP test with the expected behaviour described by the manufacturer.
2. Inspect the pump sense connector and wiring for corrosion, loose terminals, damaged insulation, or intermittent contact.
3. Check whether the sense signal changes consistently when the pump is commanded, using scan-tool data or the manufacturer's test procedure.
4. Test the sense circuit for poor continuity, shorts, or unwanted resistance at connectors.
5. If the circuit checks out, test the leak detection pump's feedback response against the manufacturer's specification.

Common fixes

• Clean or secure a loose or corroded pump sense connector.
• Repair damaged sense-circuit wiring or a poor terminal connection.
• Repair an intermittent short or high-resistance connection found in the sense circuit.
• Replace the leak detection pump if its feedback response is confirmed to be out of range.

Can I keep driving?

The range or response fault usually does not affect drivability, so normal driving is generally possible. The EVAP leak check may not complete correctly, increasing emissions and potentially preventing an emissions inspection from passing.