The evaporative emission (EVAP) control system traps and holds gasoline vapors. These vapors are routed to a charcoal canister. They pass through the intake airflow where they’re burned inside the engine instead of being released into the atmosphere.
Diagnostic trouble code (DTC) P2400 stands for “Evaporative Emission System Leak Detection Pump Control.”
Some Toyota and Dodge vehicles have a vacuum-operated leak detection pump to help diagnose the EVAP control system. The pump comes with a vent valve that’s normally open to let fresh air pass through before it reaches the charcoal canister. The charcoal canister can be found under the hood or vehicle and comes with activated charcoal granules to help trap fuel vapors.
The leak detection pump has a spring attached to a diaphragm, which applies pressure to the fuel tank. Once the PCM notices that the pressure has dropped in the fuel tank, it will trigger the leak detection pump switch. Large leaks will cause the pump to work in shorter pump periods, while small leaks will lead to longer pump periods.
Early (pre-OBD2) systems only purged the canister when the engine was above idle and warm. OBD2 systems may purge the canister any time the engine is running, even at idle.
That’s why it’s important not to “pack” the fuel tank, but let the nozzle stop when it clicks off. If you pack the tank, you can saturate the canister with fuel. The purge system doesn’t know this and if it begins to purge at idle, the engine may almost stall and then over-correct with the idle speed control, causing the vehicle to surge ahead unexpectedly at a traffic light or a drive-thru. Again, it’s best not to pack the gas tank.
Note: The definition of code P2400 might be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.
For more information about the P2400 code, read our notes on the leak detection pump.
In vehicles like the 2006 Audi A4 Quattro with a 2.0L tank, the P2400 code is described as “Evaporative Emission System Leak Detection Pump Control Circuit/Open.”
To diagnose the issue, experts recommend inspecting the EVAP canister system for seal leaks. There should also be a signal voltage greater than 4.4-5.6V if a digital multimeter is used to check the system.
DTC P2400 is a generic powertrain code that can be logged in vehicles with an OBD-II system. While this might be the case, steps for diagnosis and repair can vary, depending on vehicle specifications.
Diagnosing a P2400 code might require the use of a scan tool and visually inspecting the affected system for leaks and shorted wiring. If you’re not used to handling such tasks, you can always seek the help of a trained professional to assist you. Otherwise, you can go ahead and do the job yourself.
Without the right tools and automotive know-how, attempting to fix a P2400 code can be tricky. It can even lead to further complications if done incorrectly. So if you’re not well-versed in automotive repair yet, it might be best to leave the job to the pros. This will ensure that all steps and protocols are followed correctly.
But if you know your way around trouble codes, then you already know how important vehicle-specific repair manuals are. So before resolving this code on your daily driver, make sure to check out guides like those from Chilton or an ALLDATA subscription to get guides that are tailor-fit for your vehicle’s year, make, and model.
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