OBD-II Code
P2405
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.
P2405 means the ECM is seeing the LDP pressure-sense signal pinned at or below the lower voltage limit — usually under 0.2V when a working sensor should be reading 2.3-2.7V at atmospheric rest.
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 procedureP2405 means the ECM is seeing the LDP pressure-sense signal pinned at or below the lower voltage limit — usually under 0.2V when a working sensor sho…
P2405 means the ECM is seeing the LDP pressure-sense signal pinned at or below the lower voltage limit — usually under 0.2V when a working sensor should be reading 2.3-2.7V at atmospheric rest. The code typically indicates a short to ground on the signal wire, a failed sensor element that's collapsed to ground, or an open 5V reference upstream of the sensor that's left the signal pulled to chassis through the sensor's internal divider. The expected behavior is 0.5-4.5V scaled across -10 to +10 inH2O of EVAP pressure; a P2405 signature is a flat 0.0-0.2V reading with no movement during commanded pump cycles.
Cheapest-first ladder
- back-probe the 5V reference pin at the sensor and verify 4.95-5.05V (no reference = ECM-side fault or shared-reference short on another sensor that's pulling the whole rail down), unplug the sensor and check whether the signal pin rises to the ECM bias level (rises = sensor is internally shorted, stays at 0V = harness short to ground), and visually inspect the signal-wire run for chafe-through against the chassis.
- 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 remember that a shared 5V reference pulled down by another sensor (often a fuel-tank pressure sensor on the same bus) will set P2405 alongside other low-voltage codes — diagnose the cluster, not the single code.
Vehicle-specific patterns1998-2009 VW/Audi (Jetta, Passat, Golf, A4, A6) throws P2405 from water intrusion that bridges the signal pin to the connector shell ground inside th…
- 1998-2009VW/Audi (Jetta, Passat, Golf, A4, A6) throws P2405 from water intrusion that bridges the signal pin to the connector shell ground inside the rear-axle LDP housing.
- 1998-2008Chrysler/Jeep/Dodge (Sebring, Wrangler, Grand Cherokee) NVLD/LDP combination units throw P2405 from an internally-shorted pressure transducer — the unit is non-serviceable.
- 1996-2005Mercedes-Benz (W202, W203, W211) throws P2405 from a chafed signal wire where the EVAP loom passes the rear muffler hanger, with the wire grounding to the exhaust shield. 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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