Diagnostic article Generic OBD-II
P2404: leak-pump feedback depends on vacuum, power and purge sealing
Ross-Tech's P2404 reference includes electrical supply, vacuum supply and purge leakage, so a pump-sense fault does not automatically require a new pump.
Read before applying this article
Documented application
Ross-Tech independent VAG diagnostic guidance; match complete fault description and controller. Vehicle-specific notes do not establish universal applicability.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P2404 concerns implausible feedback from EVAP leak-detection pump V144 in Ross-Tech's VAG reference. The page separates electrical and mechanical pump failure from missing voltage, inadequate vacuum, an EVAP pressure leak and a leaking N80 purge valve. These are distinct reasons the expected pump response may be absent.
Establish what the pump receives
Ross-Tech recommends checking electrical supply and, where fitted, engine-component relay J757. It also calls for checking the vacuum supply at idle. A pump cannot be judged solely by its name in the code if its required supply is missing. The reference specifically highlights J757 on some Audi A6 applications.
A purge leak can undermine the test
The source includes testing whether N80 leaks system pressure into the intake manifold. That observation distinguishes leakage through the purge path from a defective leak-detection pump. It also explains why an electrical resistance check alone cannot resolve every P2404.
Vehicle notes include BPY engines and a particular Touareg coolant-pump concern; neither applies automatically to all models. Use the actual repair manual for electrical, vacuum and pressure limits. This article follows independent Ross-Tech guidance and does not prescribe replacing V144 before its supplies and the relevant system leakage are assessed.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
EVAP System Leak Detection Pump Sense Circuit Range/Performance
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT