Diagnostic article Generic OBD-II
P2403: low leak-pump sense feedback must persist in Audi's CTUA monitor
Audi's CTUA P2403 criterion concerns low sense-circuit voltage lasting more than one second, which differs from directly finding an EVAP leak.
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Documented application
Audi 2014 A6/S6 Quick Reference Specification Book, September 2013, Engine Code CTUA, DTC chart. Thresholds only describe this documented monitor; not universal across other makes or engines.
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.
P2403 is an EVAP leak-detection pump sense-circuit or open-circuit fault. Audi's CTUA diagnostic chart lists low signal voltage persisting for more than one second. The criterion combines an electrical state with duration; it does not specify a vapor-leak size.
Sense feedback is different from pump control
The table separately lists pump-control faults, while this entry concerns the sense path. As diagnostic interpretation, confirming that the pump receives a command does not independently establish that its feedback is credible. Likewise, a sense-circuit fault is not direct evidence that the fuel cap or tank has a leak.
The one-second condition is also meaningful. A momentary low sample does not, by itself, reproduce the persistence described in this particular row.
Do not invent the missing voltage limit
Audi's CTUA entry calls the signal low but does not publish a numerical voltage boundary here. That should not be filled with a guessed value or a threshold from another engine. Use the applicable repair procedure to assess the actual circuit and test state. This monitor explanation is limited to the CTUA section of the 2014 Audi A6/S6 book and does not prescribe pump replacement simply because its sense feedback was abnormal.
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/Open
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