OBD-II Code
P2403
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$200–$750
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
P2403 means the ECM is seeing an open circuit on the LDP pressure-sense feedback line — the sensor that reports tank/system pressure back to the ECM during the leak test is either disconnected, has a broken signal wire, or the sensor element itself is open internally.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureP2403 means the ECM is seeing an open circuit on the LDP pressure-sense feedback line — the sensor that reports tank/system pressure back to the ECM…
P2403 means the ECM is seeing an open circuit on the LDP pressure-sense feedback line — the sensor that reports tank/system pressure back to the ECM during the leak test is either disconnected, has a broken signal wire, or the sensor element itself is open internally. The LDP sense circuit is a 0-5V analog signal that scales linearly across roughly -10 to +10 inH2O of EVAP system pressure (most platforms idle around 2.5V at atmospheric); a clean open reads as 5.0V (pulled up) or 0.0V (floating) depending on the ECM's bias scheme, and that's the signature the code is flagging.
Cheapest-first ladder
- locate the LDP sense connector (typically a 3-pin: 5V reference, signal, ground), back-probe the 5V reference pin and confirm 4.95-5.05V at KOEO (no voltage = ECM reference fault or short downstream), back-probe the signal pin and confirm a stable 2.3-2.7V at atmosphere with the system vented, then key-off and watch the signal climb during a commanded pump cycle (a working sensor sweeps to roughly 3.5-4.0V at +5 inH2O of test pressure).
- If reference and ground are good but signal is stuck at rail, the sensor element is open.
- Expensive misdiagnosis caveat: VW/Audi/Chrysler LDP is mounted in a notorious water-collection point above the rear axle — corrosion at the connector is the #1 root cause; replace the pigtail before replacing the pump, and verify the sense and control connectors are not cross-swapped after a previous repair (an easy mistake on combined assemblies).
Vehicle-specific patterns1998-2009 VW/Audi (Jetta, Passat, Golf, A4, A6) throws P2403 from a broken sense-wire pin inside the rear-axle LDP connector — the pin backs out of t…
- 1998-2009VW/Audi (Jetta, Passat, Golf, A4, A6) throws P2403 from a broken sense-wire pin inside the rear-axle LDP connector — the pin backs out of the housing during a harness disturbance and the ECM sees it as open.
- 1998-2008Chrysler/Jeep/Dodge (Sebring, Wrangler, Grand Cherokee) combined NVLD/LDP units throw P2403 when the internal pressure-switch contacts oxidize and fail open.
- 1996-2005Mercedes-Benz (W202, W203, W211) throws P2403 from a cracked sensor housing on the canister-integrated LDP, often after a rear-bumper repair that disturbed the unit. Common LDP repair pattern: replace pump + harness pigtail together; standalone pump replacement leaves the same root cause.
Estimated repair$200 to $750.
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