P2403Generic code

P2403 Code: Evaporative Emission System Leak Detection Pump Sense Circuit

The P2403 code means the computer found an electrical fault in the sensor circuit of the EVAP leak detection pump. The main effect is that the EVAP monitor does not complete. It does not affect how the car drives.

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 P2403 code means

On many vehicles the EVAP system is tested with a small pump (an LDP or an ELCM) that pressurizes the tank and hoses or pulls a vacuum on them with the engine off or idling. By measuring how long it takes to reach pressure and how long the pressure holds, the computer can detect leaks as small as half a millimeter (about 0.02 inch).

The sensor works as a switch: the computer sees a high or a low voltage depending on its position. A circuit fault can come from the sensor, the wiring or the power supply, and it is what the P2403 code reports.

The computer reads a switch or a pressure sensor inside the pump to learn whether it reached the test pressure.

Always start with the simplest things: fuse, relay and connector. Then check power, ground and signal with the component plugged in (using back-probes), and last the continuity of each wire to the computer. Only if all of that checks out should you replace the component.

P2403 code symptoms

  • Check engine light on.
  • The EVAP monitor does not complete.

Likely causes of the P2403 code

  1. Damaged or corroded connector. The most common cause.
  2. Cut or shorted wiring between the sensor and the computer.
  3. Failed sensor. Open or internally shorted.
  4. Missing power reference. Check whether other sensors are also failing.
  5. Computer. Uncommon, so rule out everything above first.

How to diagnose the P2403 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 power and ground with the key on: correct reference voltage and less than 0.1 V drop on the ground.
  4. Measure the signal with the connector plugged in and see whether it changes with the conditions.
  5. Do a wiggle test on the wiring with the scan tool in graph mode.
  6. Check the continuity of each wire to the computer (less than 1 ohm).

How to fix the P2403 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.

After the repair, run the EVAP monitor and make sure the P2403 code stays away. The monitor can take a few drive cycles to complete.

Technical reference data

  • 12 V supply from a relay or from the computer.
  • Many pumps include a switching valve and a pressure sensor.
  • These are reference values only: check the manufacturer data for your vehicle.

Brand-specific notes

This code is common on makes that use a leak detection pump or a leak detection module near the canister.

P2403 on Chrysler

Frequent on Chrysler vehicles, which use an LDP pump.

P2403 on Dodge

Frequent on Dodge vehicles, which use an LDP pump.

P2403 on Jeep

Frequent on Jeep vehicles, which use an LDP pump.

P2403 on Volkswagen

Frequent on Volkswagen vehicles.

P2403 on Audi

Frequent on Audi vehicles.

P2403 on Toyota

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

Frequently asked questions about P2403

Can I drive with a P2403 code?
Yes. It does not affect how the vehicle drives, but the EVAP monitor will not complete until it is repaired.
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.
What does the EVAP leak pump sensor do?
On many vehicles the EVAP system is tested with a small pump (an LDP or an ELCM) that pressurizes the tank and hoses or pulls a vacuum on them. A switch or pressure sensor inside the pump tells the computer whether the test pressure was reached, which is how it detects leaks as small as half a millimeter.
How much does it cost to fix P2403?
Roughly $60 to $400. A connector or wiring repair is at the low end, and a new pump with labor is closer to the top.
What does the P2403 code mean?
It is a generic OBD2 code that means there is an electrical fault in the circuit of the EVAP leak detection pump sensor. The fault can be in the sensor, the wiring or the power supply.
Will a P2403 code clear itself?
If the fault was a momentary glitch, the light can go out after several drive cycles. A damaged connector or wire will bring it back, so find the cause.
What is the most common cause of P2403?
A damaged or corroded connector. Check it before you spend money on a new pump.

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