OBD-II Code P2400 — What It Means & How to Fix It

What it means

The EVAP system prevents fuel vapors from escaping into the atmosphere, and some vehicles use a small pump to actively check for leaks.
P2400 means the ECM detected an open circuit in that pump's control wiring — the pump can't be commanded on or off.
This won't affect how the car drives, but the check engine light will stay on and you'll likely fail an emissions test.

Affected Models

All vehicles 1996+ with EVAP leak detection pump
Common in Subaru vehicles
Common in some Nissan models
Common in some European vehicles with active EVAP testing

Common Causes

Broken or disconnected wire in the leak detection pump circuit
Blown fuse supplying power to the EVAP pump
Failed leak detection pump with an open internal circuit
Corroded connector at the pump harness
Failed ECM relay or driver for the EVAP pump circuit

How to Fix It

Check the fuse for the EVAP system — replace if blown.

A blown fuse causes an open circuit to the pump — always check the fuse box first before spending time on other checks.
Locate the leak detection pump and inspect its wiring harness.

The pump is usually near the charcoal canister under the hood or near the fuel tank — check your service manual for its exact location.
Test for power and ground at the pump connector with a multimeter.

If power and ground are present but the pump doesn't run, the pump motor has failed internally.
Check circuit continuity from the pump connector back to the ECM.

An open (infinite resistance) reading on the control wire indicates a broken wire that needs to be found and repaired.
Replace the leak detection pump if it has an open internal circuit.

After replacement, clear the code and run the EVAP monitor through a complete drive cycle to confirm the repair.

When to Call a Professional

If fuse and wiring checks don't resolve the code, have a mechanic locate the pump and test it directly.
Diagnosis involves checking power, ground, and control signal at the pump connector.
Expect $80–$130 for diagnosis; replacement pumps cost $30–$120 and are usually easy to access.

Frequently Asked Questions

Can I drive with P2400?

Yes, this code does not affect how the car drives.
But the check engine light will stay on.
Fix it before your next emissions test.

Where is the leak detection pump located?

Usually near the charcoal canister in the EVAP system.
On most vehicles it's under the hood or near the fuel tank.
Check a service manual for your specific vehicle.

How much does a leak detection pump cost?

Aftermarket pumps typically cost $30–$120.
Dealer parts can be higher.
Labor is usually minimal as the pump is easy to access.