OBD-II Code
P2406
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.
P2406 means the ECM is seeing the LDP pressure-sense signal pinned at or above the upper voltage limit — typically over 4.8V when a working sensor should read 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 procedureP2406 means the ECM is seeing the LDP pressure-sense signal pinned at or above the upper voltage limit — typically over 4.8V when a working sensor sh…
P2406 means the ECM is seeing the LDP pressure-sense signal pinned at or above the upper voltage limit — typically over 4.8V when a working sensor should read 2.3-2.7V at atmospheric rest. The code indicates either an open signal-return (ground) circuit at the sensor, a short to the 5V reference on the signal wire, or a failed sensor that's internally collapsed to its supply rail. Expected scaling is 0.5-4.5V across -10 to +10 inH2O of EVAP pressure; a P2406 signature is a flat reading at 4.9-5.0V regardless of commanded pump activity.
Cheapest-first ladder
- back-probe the sensor ground pin and verify continuity to chassis ground (more than 0.5 ohms = open or high-resistance ground return), unplug the sensor connector and check whether the signal pin drops toward 0V (drops = sensor is the fault, stays high = harness short to 5V), and inspect the connector for a swapped pin or a pushed-back terminal.
- 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, because a green-rotted ground pin reads as open and sets P2406 even though the sensor and ECM are both good.
Vehicle-specific patterns1998-2009 VW/Audi (Jetta, Passat, Golf, A4, A6) throws P2406 from corroded ground-return pins inside the rear-axle LDP connector — the ground path op…
- 1998-2009VW/Audi (Jetta, Passat, Golf, A4, A6) throws P2406 from corroded ground-return pins inside the rear-axle LDP connector — the ground path opens up and the signal floats to reference voltage.
- 1998-2008Chrysler/Jeep/Dodge (Sebring, Wrangler, Grand Cherokee) combined NVLD/LDP units throw P2406 from internal sensor failure that pins the output to the 5V rail.
- 1996-2005Mercedes-Benz (W202, W203, W211) throws P2406 from a failed sensor ground splice inside the rear underbody harness — the splice is buried under a heat shield and frequently corrodes. Common LDP repair pattern: replace pump + harness pigtail together; standalone pump replacement leaves the same root cause.
Estimated repair$200 to $750.
Look up another code
More free tools