Boxster Tips

P2402 Leak Detection Pump Error

Boxster P2402 Leak Detection Pump Error is a problematic repair. Clear the Check Engine Light (CEL) error and see if the error happens again.

My 2009 Boxster S started getting P2402 Leak Detection Pump (LDP) errors. on a regular basis.

I would clear the errors using an OBDII tool and the error would always return. The ODBII error is indicative that I have a failed Vapor Leak Detection Pump (PN# 997-605-125-01).

With this error I noticed no difference in the performance of my Boxster.

Check Your Gas Cap

Initially, you should check your gas cap for tightness and replace it if the rubber ring is worn or cracked. It is important to get a proper seal when closing your gas cap. Make sure you hear a minimum of 3-5 clicks when closing your gas cap. Your gas tank has to achieve an airtight seal.

What is Leak Detection Pump and How it Works

Evaporative emissions control or EVAP systems are a part of your car’s emission control since the 1970s. The EVAP system prevents fuel tank vapors from venting into the atmosphere. It collects and stores these gas vapors and, at the correct time, and moves them to the intake manifold for combustion or the return to the gas tank. The EVAP systems have changed over the years, evolving from simple fuel tank vacuum-operation to a fully sealed, OBD2 monitored, and ECM controlled systems. Fuel filler caps are non-venting and have a positive and negative pressure relief valve built-in.

What is Leak Detection Pump used for?

Porsche uses the Leak Detection Pump to pressure the EVAP system to perform diagnosis. This system works by pumping pressurized air into the EVAP system to test it for leaks. The Leak Detection Pump has a series of one-way valves and a vent valve, a sensor at the top, a vacuum solenoid, and a spring-loaded diaphragm. It uses an engine vacuum to move the diaphragm up and down. This motion, controlled by the solenoid, pressurizes the EVAP system. When the pump reaches a specific amount of pressure, it will stop the up-and-down movement and close the vent valve at the bottom of the pump. This seals the EVAP system, and the ECU starts the monitoring procedure.

During this time, the pressure within the system must remain above a preset value. If it passes, the ECU activates the vacuum solenoid placed at the top of the LDP pump and releases the pressure from the EVAP system. When this happens, the diaphragm will also push on the vent valve, allowing fresh air from outside to enter the system.

EVAP and ODBII

The pressures inside the EVAP system during the ODBII monitoring process is low. The entire pump is calibrated to pump a certain amount of pressure and stay in the up position after reaching that pressure. This system differs from one used by other manufacturers is that it doesn’t rely on a fuel tank pressure sensor to do the EVAP testing. The ECU looks at a sensor reading as an indicator of the pressure, since it knows that the diaphragm will have to stay in the up position when the system is pressurized.

Any changes in these readings will mean there is a leak. If the pump cannot reach the preset pressure, the ECM will know according to the severity of the signal that there is an impending large EVAP leak. This is why cars with this system can issue a code such as a large leak detected or a small leak detected. The ECM monitors the frequency output of the read switch to determine how big the leak is.

Failed Vapor Leak Detection Pump

Location of the Leak Detection Pump (part # 19)
Location of the Leak Detection Pump (part # 19)

The OEM Porsche part is very expensive, at over $200 USD. I ordered the Bosch equivalent part W0133-3591723 (1/3rd the price of the OEM Porsche Part 97-605-125-01) and decided to replace it. I sourced the part from the internet and used Parts Geek.

If you are sourcing the OEM part make sure you use your PCA Membership number to get a further 10%-25% discount from your dealer’s parts desk.

W0133-3591723 Bosch Leak Detection Pump
W0133-3591723 Bosch Leak Detection Pump

Unfortunately, the Boxster Leak Detection Pump part is located inside the Carbon Canister and the Carbon Canister is located in the Frunk.

It took me an hour to do the work. I would not recommend this to the average DIYer as it is a tricky install if you have not done it before.

The carbon canister is sealed using metal clips. it is not easy to remove or to replace these clips. As you remove the clips they are prone to high velocity as they are ejected. You need very strong fingers to get the sheet metal clips back on once the LDP is replaced. Not to mention getting them off in the first place.

2 years later and I am Boxster P2402 Leak Detection Pump Error code free. In my research, some people have eluded to that this issue comes on if you fill the tank too full. I am guilty of doing this on a regular basis, during my long trips.

Under no circumstances should you fill any car’s fuel tank after the nozzle shuts off.

Common problems

The Boxster P2402 Leak Detection Pump Error is a common failure point. Usual causes are diaphragm rupture, inoperable solenoid, or jammed valves. When any of these parts fail, replacing the pump is the only viable option. Still, outside issues, such as broken vacuum lines or poor electrical connections can make this system inoperable.

Don’t Overfill Your Gas Tank

Don't Overfill Your Gas Tank
Don’t Overfill Your Gas Tank

We have all seen this happen, or have done this from time to time. When refueling, we keeping clicking the gas pump handle to either round off the price, or make sure we have it filled to the maximum volume. Sometimes people get frustrated when the handle keeps shutting off before they think filling the tank is done.

Doing this can cause a blocked or defective fuel tank vent system. As fuel enters a tank, it displaces any air inside and it must find an escape route. As the air in any fuel tank is considered an environmental hazard, automakers use systems to control and capture these fumes to keep them from being expelled into the atmosphere.

If you’ve over-fill your gas tank, you risk contaminating the carbon canister with liquid fuel. When fuel gets into the carbon, things don’t flow well. You shouldn’t fill much past where the pump shuts off the fuel.

Evaporative Emissions Controls Systems

These systems are known as evaporative emissions controls. These systems consist of an air-tight canister mounted under the vehicle near the tank. An electric pump creates a vacuum to draw fuel vapors into the canister, where they collect into liquid form to be returned into the tank.

When these systems fail, they can pressurize the tank, keeping fuel from easily entering via the filler neck. If you’ve ever removed a gas cap and gotten a substantial rush of air outward, this system needs attention.

There is nothing you can do to maintain these emission control components or prevent their component failures, with one exception. Do Not fill an excessive amount of fuel into a tank. On a hot day, this can overload the vapor control systems.

When fuel travels from the underground storage tank to your vehicle’s tank, the temperature can rise dramatically and this increase will cause more pressure from evaporative fumes. The canisters that hold these vapors have a limited amount of space, and if they can’t complete their task, they may trigger a ‘check engine’ light (CEL) — or even pop off a vent line. Few of these lines are ever clamped down because they’re not expected to be subjected to higher pressures.

Critical Point: When the gas pump handle clicks the first time, you are done refueling.

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