OBD-II Code · Emissions
P2404
EVAP Leak Detection Pump Sense Circuit Range
Severity
low
Lowest on our scale. Fix it when convenient.
Can you drive it
Only if running normally
A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety.
Indicative cost (USD)
$150–$400
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
Leak detection pump sense out of range.
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 work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
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
Likely causes
- Failed pumpMost common
- Wiring
Read the full diagnostic procedureP2404 means the ECM is seeing the LDP pressure-sense signal in range electrically (it's not pegged high or low) but the value is not behaving the way…
P2404 means the ECM is seeing the LDP pressure-sense signal in range electrically (it's not pegged high or low) but the value is not behaving the way the ECM expects during a commanded pump cycle — typically the signal isn't moving when the pump activates, or it's drifting in ways that don't correlate with the test sequence. A healthy sense signal reads 2.3-2.7V at atmospheric rest, climbs to roughly 3.5-4.0V when the pump pressurizes the system to about +5 inH2O during the leak test, and decays back to atmospheric over the test window (typically 30-180 seconds); the ECM flags P2404 when the signal stays flat during commanded pump operation or doesn't decay at the expected rate.
Cheapest-first ladder
- data-log the sense voltage during a bidirectional pump activation (flat line = blocked sense port, no pump action, or clogged canister vent), perform a smoke-test of the EVAP system to verify the pump can actually build pressure (a sealed cap missing means the pump never reaches threshold), and inspect the canister vent valve for stuck-open condition (vent stuck open = pump can't build pressure regardless of how good the sensor is).
- 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 rule out a stuck-open canister vent solenoid before condemning the sense element.
Vehicle-specific patterns1998-2009 VW/Audi (Jetta, Passat, Golf, A4, A6) throws P2404 from a clogged sense port inside the rear-axle LDP — water or canister carbon migrates i…
- 1998-2009VW/Audi (Jetta, Passat, Golf, A4, A6) throws P2404 from a clogged sense port inside the rear-axle LDP — water or canister carbon migrates into the sense passage and the sensor stops responding to pressure changes.
- 1998-2008Chrysler/Jeep/Dodge (Sebring, Wrangler, Grand Cherokee) NVLD/LDP combination units throw P2404 when the internal diaphragm tears and the sensor sees no delta during a pump cycle.
- 1996-2005Mercedes-Benz (W202, W203, W211) throws P2404 from a stuck canister vent valve that never closes for the leak test, leaving the system unable to build any pressure for the sensor to read. Common LDP repair pattern: replace pump + harness pigtail together; standalone pump replacement leaves the same root cause.
Estimated repair$220 to $800.
Look up another code
P2404 — frequently asked
What does a P2404 code mean?
Leak detection pump sense out of range.
What causes a P2404 code?
Common causes: Failed pump; Wiring.
What are the symptoms of a P2404 code?
Typical symptoms: Check engine light.
Is it safe to drive with a P2404 code?
Only if running normally. A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety. Estimated repair: $150-$400.
How do I diagnose a P2404 code?
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. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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