P2400 Code: EVAP Leak Detection Pump Control Circuit/Open
The engine computer can't drive the EVAP leak detection pump – usually a broken wire, bad plug or dead pump.
At a glance
Severity: Low
- Meaning
- EVAP Leak Detection Pump Control Circuit/Open
- System
- Emission Controls · Powertrain
- Safe to drive?
- Yes, short term
- Typical repair cost
- $20–$1,300
- DIY difficulty
- Moderate
Many vehicles check the fuel vapor system for leaks with a small leak detection pump (LDP) mounted on or near the charcoal canister. On older Chrysler, Dodge and Jeep models and some VW/Audi it is a vacuum-driven diaphragm pump with a solenoid; Toyota, Lexus and several European makes use an electric pump module instead. The engine computer switches that solenoid or motor on and watches the control line; P2400 means the circuit behaves as if it were open – no current flows when the pump is commanded. The EVAP leak test can't run at all while this code is present, so no leak codes will be reported either.
Can I keep driving? The car drives normally and nothing gets damaged. The only real cost of waiting is that the EVAP monitor stays incomplete, so plan the repair before your next emissions test.
How to read P2400
- P Powertrain
- 2 Generic (SAE)
- 4 Auxiliary emission controls
- 00 Specific fault
Symptoms
- Check engine light on, engine runs normally
- EVAP monitor shows 'not ready' or 'incomplete' on a scan tool
- Code returns right after clearing, often on the first key-on or first drive
- Code sometimes appeared after underbody work, a tow hitch install or driving through deep water
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Corroded or loose connector at the leak detection pump – it sits under the car in road spray
- Broken or chafed wire in the harness running to the canister area
- Open solenoid coil or burned-out pump motor inside the LDP
- Blown fuse or failed relay feeding the pump's 12-volt supply
- Connector left unplugged after fuel tank, exhaust or hitch work
- Faulty driver inside the engine computer (rare)
Diagnosis step by step
Confirm the code and look for companions
Scan all modules and note whether P2401, P2402 or P2404 are stored too. P2400 on its own points to an open circuit; several pump codes together make a wiring or supply problem more likely than a bad pump.
Tools: OBD-II scanner
Find the pump and inspect the plug
Follow the vapor hoses from the canister; the LDP is clipped to it or mounted close by, near the tank or in a wheel well depending on the model. Unplug it and look for green corrosion, pushed-back pins or water in the connector.
Tools: Flashlight, Screwdriver
Check the 12-volt feed
Key on, engine off: one pin in the harness plug should show battery voltage (about 12 to 12.6 V). No voltage sends you to the fuse and relay chart before anything else.
Tools: Multimeter
Measure the solenoid or motor
Measure resistance across the pump's control and feed pins. A vacuum-type LDP solenoid typically reads a few tens of ohms and an electric pump motor only a few ohms; 'OL' or infinite means the part is open inside.
Tools: Multimeter
Test the control wire to the computer
With the battery disconnected, check continuity from the pump plug to the matching pin at the engine computer. Anything above roughly 1 ohm, or a reading that comes and goes when you flex the harness, means a wiring repair.
Tools: Multimeter
Command the pump and verify
If your scan tool offers an EVAP or LDP output test, switch the pump on and listen for clicking or humming at the canister. After the repair, clear the code and let the car sit overnight and complete a few drives so the EVAP monitor can finish.
Tools: OBD-II scanner
Where the parts are
- 1Gas cap
- 2Charcoal canister
- 3Purge valve
- 4Vent valve
- 5Fuel pump
- 6Intake manifold
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Clean and reseat or repin the pump connector | Yes | $20–$120 |
| Repair chafed or broken harness wire | No | $100–$300 |
| Replace leak detection pump (vacuum LDP type) | Yes | $150–$400 |
| Replace electric canister pump module | No | $250–$650 |
| Repair or replace engine computer | No | $500–$1,300 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Notes by brand
Jeep
Jeep, Dodge and Chrysler models with the vacuum-operated LDP mount it next to the canister, where mud and salt attack the three-pin connector. Cleaning the plug fixes a fair share of circuit codes before a new pump is needed.
Emissions / smog test impact
Will fail
With P2400 stored the check engine light is on, which fails an OBD-based smog check outright, and the EVAP monitor can't run until the circuit is fixed. Clear the code only after the repair and allow a few days of driving before the retest.
Frequently asked questions
Is the leak detection pump the same as the purge valve?
No. The purge valve lets stored vapor into the engine while driving; the leak detection pump pressurizes or tests the sealed system for leaks. They sit in different places and have different codes.
Why does my car show no leak codes even though the EVAP system could leak?
With the pump circuit open, the leak test simply doesn't run. Once P2400 is fixed, an existing leak can show up as P0442, P0455 or P0456 during the next test cycles.
Can I just leave the pump unplugged?
The car will run, but the light stays on, the EVAP monitor never completes and the car fails any OBD emissions test. It's a cheap circuit to repair, so it's not worth leaving.
Why did P2400 appear after winter?
The pump lives under the vehicle, and road salt and slush get into its connector. Corroded terminals are the most common reason the circuit reads open.