P2404

EVAP Leak Detection Pump Sense Circuit: Implausible Signal

P2404 is a generic OBD-II powertrain diagnostic trouble code: EVAP Leak Detection Pump Sense Circuit: Implausible Signal. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P2404
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P2404 means

P2404 is set when the ECM detects that the signal from the evaporative emission (EVAP) leak detection pump sense circuit is outside the expected range or does not respond as expected during an EVAP integrity test. Some EVAP system designs use an electric pump to pressurise or create a vacuum in the fuel tank and vapour lines so the ECM can detect leaks by monitoring pump current draw or a dedicated sense signal.

The code specifically targets the sense or feedback circuit of the pump rather than raw pump operation, meaning the pump motor may run but the circuit that reports pump load, vacuum achieved, or switch state is giving an implausible signal. Faults range from a defective pump assembly with an internal sensor fault, to wiring issues between the pump and ECM.

Diagnosis should begin with a visual inspection of the EVAP system for obvious leaks or disconnected hoses, followed by electrical checks on the pump sense wiring. If the EVAP system is physically intact, testing or replacing the leak detection pump assembly is often the resolution because the sense element is integral to the pump on many designs.

Common causes

Most-frequently reported root causes when P2404 is logged.

  • 1
    Faulty EVAP leak detection pump with a defective internal sense element.
  • 2
    Open or short in the pump sense signal wiring between the pump and ECM.
  • 3
    Corroded or damaged pump connector affecting the sense circuit.
  • 4
    EVAP system blockage preventing the pump from building expected pressure or vacuum.
  • 5
    Fuel cap not fully seated, introducing a large leak that overwhelms the pump.
  • 6
    Faulty ECM sense input circuit.
  • 7
    Moisture or fuel contamination inside the EVAP pump assembly.

Symptoms drivers notice

MIL illuminated.
EVAP monitor not completing, preventing readiness for emissions testing.
Possible mild fuel odour if an EVAP leak is also present.
No driveability issues typically associated with this code.

How to diagnose P2404

A typical diagnostic flow when this code is present.

  1. 1
    Read all DTCs and freeze-frame data; note if additional EVAP codes are present alongside P2404.
  2. 2
    Inspect the fuel cap to confirm it seals properly.
  3. 3
    Visually inspect all EVAP hoses and connections for cracks, kinks, or disconnections.
  4. 4
    Inspect the EVAP leak detection pump wiring harness and connector for damage or corrosion.
  5. 5
    Measure sense circuit voltage and compare to specification with the key on.
  6. 6
    Command the EVAP pump on via the scan tool and monitor the sense signal for a response.
  7. 7
    Replace the EVAP leak detection pump assembly if the pump runs but no valid sense signal is produced.

Vehicles where we've handled P2404

Platforms in our catalogue with confirmed P2404 coverage.

BMW 320D
2016

Related powertrain codes

Frequently asked questions

Can a loose fuel cap set P2404?

A loose cap may contribute to EVAP faults but P2404 is specifically a sense circuit range or performance fault; a loose cap alone more commonly sets P0457 or P0455.

Where is the EVAP leak detection pump located?

Location varies by manufacturer; it is commonly found near the charcoal canister, at the rear of the vehicle near the fuel tank, or integrated into the EVAP canister assembly.

Is P2404 a serious code?

It is emissions-related and will cause MIL illumination and a failed readiness check, but it does not affect engine performance or create a safety hazard.

Can I clear P2404 without repair?

The code will return on the next EVAP monitor run if the underlying fault is not corrected; clearing without repair only temporarily extinguishes the MIL.

Disabling P2404 in software

RaceTune can permanently disable P2404 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

ECUs with a P2404 disable in our catalogue

Confirmed coverage from our recipe database — we support many more families. Upload your file and our identifier will match it automatically.

  • Bosch EDC17C50 verified 1 software version
  • Bosch EDC17CP09 verified 1 software version

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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