P2400

P2400 means the ECM is trying to drive the EVAP Leak Detection Pump (LDP) and is seeing an open circuit on the control side — no current draw at all when the driver should be pulling the solenoid down to ground. On a typical platform the LDP control circuit measures 30-80 ohms across the solenoid winding with the connector unplugged (cold), and the ECM should see roughly 0.3-0.8A of current draw when it commands the pump on during the post-shutdown leak test (vehicle off, key out, 5-45 minutes later). The pump motor itself spikes to 0.5-2A momentarily as it builds the test pressure. Cheapest-first ladder: pull the LDP connector and visually inspect the pigtail for green corrosion (this is the #1 finding on rear-axle-mounted units), measure pump-side resistance across the two control pins (anything outside 30-80 ohms = bad solenoid/coil), back-probe the connector with the ignition in KOEO and verify 12V on the supply pin (no voltage = blown fuse or open in the power feed from the EVAP relay), then key-on the bidirectional scan-tool LDP activation test and watch for the current reading. An 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, so replace the pigtail before replacing the pump or you will swap a $300 part and have the code back within a week.

Vehicle-specific patterns: 1998-2009 VW/Audi (Jetta, Passat, Golf, A4, A6) with the rear-axle-mounted LDP is the textbook P2400 ticket — road spray and salt rot the connector pins from the inside out, and you can pull the harness boot and find the copper green to the touch. 1998-2008 Chrysler/Jeep/Dodge (Sebring, Wrangler, Grand Cherokee) use a combined NVLD/LDP unit that's notorious for an internal solenoid coil break — the unit is non-serviceable, but always cut and inspect the pigtail before condemning. 1996-2005 Mercedes-Benz (W202, W203, W211) integrate the LDP with the charcoal canister assembly under the rear fender liner, and a leaking vent hose dumps water directly onto the connector. Common LDP repair pattern: replace pump + harness pigtail together; standalone pump replacement leaves the same root cause. Estimated repair: $180 to $650.