P2405Generic code

P2405 Code: Evaporative Emission System Leak Detection Pump Sense Circuit Low

The P2405 code means the signal from the sensor inside the EVAP leak detection pump is below its minimum expected value. The most common cause is a sense wire shorted to ground or a missing reference voltage. The car drives normally, but the EVAP monitor cannot finish.

Severity
Low
Can I keep driving?
Yes, no immediate risk
Estimated cost
$60 to $400
Difficulty
Medium
System
Emissions Control
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P2405 code means

On many vehicles the evaporative emission (EVAP) system is tested by a small pump, called an LDP or an ELCM, that pressurizes the fuel tank and hoses or pulls a vacuum on them with the engine off or at idle. By measuring how long the system takes to reach the test pressure and how well it holds it, the computer can detect leaks as small as half a millimeter.

The computer reads a switch or a pressure sensor inside the pump to know whether the test pressure was reached. It works like a switch: the computer sees a high or low voltage depending on its position. A low signal usually comes from a short to ground on the signal wire or from a missing reference voltage. That is what the P2405 code reports.

To confirm it, unplug the component with the key on and watch what happens to the reading or the code. If the value jumps to the opposite extreme, the wiring is fine and the component itself is the one pulling the signal to ground. If nothing changes, look for the short in the wire, starting where the harness rubs against the engine, the chassis or the exhaust.

P2405 code symptoms

  • Check engine light on.
  • The EVAP monitor does not complete, so the vehicle cannot pass an emissions test that needs it ready.

Likely causes of the P2405 code

  1. Signal wire shorted to ground because the harness rubs against the engine, the chassis or a bracket.
  2. Shorted reference supply. If several sensors fail at once, suspect the shared reference voltage.
  3. Damaged sensor with an internal short.
  4. Connector with water or corrosion that creates a path to ground.

How to diagnose the P2405 code step by step

  1. Read the sensor value on the scan tool and compare it with what you expect.
  2. Inspect the connector for corrosion, water or loose pins.
  3. Check supply and ground with the key on: the reference should be correct and the ground voltage drop should be under 0.1 V.
  4. Measure the signal with the connector plugged in and see whether it changes with the operating condition.
  5. Do a wiggle test on the harness with the scan tool in graph mode.
  6. Check continuity of each wire to the computer, which should be under 1 ohm.

How to fix the P2405 code

  • Repair the connector or the wiring.
  • Replace the sensor if the tests confirm it is bad.
  • Correct the real condition if there is one.
  • Clear the codes and verify with a road test.

Technical reference data

  • 12 V supply from a relay or from the computer.
  • Many pumps combine a changeover valve and a pressure sensor in one housing.
  • Approximate values only: check the manufacturer data for your vehicle.

Brand-specific notes

The wiring and connector are as likely to be the problem as the pump itself, so test them before you buy one. The P2405 code does not hurt drivability, which makes it easy to ignore, but the EVAP monitor will stay incomplete until it is fixed.

P2405 on Chrysler, Dodge and Jeep

Common on these vehicles, which use an LDP pump.

P2405 on Volkswagen and Audi

Common on these makes as well.

P2405 on Toyota

Seen on Toyota vehicles with a leak detection module built into the charcoal canister.

Frequently asked questions about P2405

Can I drive with a P2405 code?
Yes. It does not affect how the car drives. The EVAP monitor will stay incomplete, which matters if you need to pass an emissions test.
Does the sensor have to be replaced?
Only if the tests confirm it. The connector and the wiring fail just as often as the sensor, so check them first.
What does the EVAP leak detection pump sensor do?
On many vehicles a small pump (LDP or ELCM) pressurizes or pulls a vacuum on the tank and hoses with the engine off or at idle. The computer times how long it takes to reach test pressure and how well it holds it, which lets it find leaks as small as half a millimeter. The sensor tells the computer whether the pump reached that pressure.
What does the P2405 code mean?
It means the signal from the EVAP leak detection pump sensor is below its minimum value. That usually points to a short to ground in the signal wire or a missing reference voltage.
How much does it cost to fix P2405?
Roughly $60 to $400. A wiring or connector repair sits at the low end, and a new pump or module costs more.

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