P2404

P2404

Evaporative Emission System Leak Detection Pump Sense Circuit Range/Performance

Diagnostic conditions
- Battery positive voltage between 10 V and 16 V
- In the time that elapses between stopping and restarting engine, engine must cool down by at least 42 K.
- Short journey with partial load share (3 km/h... 150 km/h)
- Intake air temperature between 5 °C and 95 °C
- Engine temperature higher than 5 °C
- Diagnosis doesn't run at altitudes higher than 2,400 m above sea level
- No P0441 (Evaporative Emission System Incorrect Purge Flow) or P0446 (Evaporative Emission System Vent Control Circuit) faults in memory
- No active charcoal filter shutoff valve, leakage diagnosis pump or EVAP canister purge valve output stage faults in memory

Possible cause of fault
- Insufficient vacuum (system has a leak or blockage)
- Short circuit to B+ in signal line
- Leakage diagnosis pump faulty (diaphragm or reed switch sticks, internal solenoid valve stays closed or is blocked)
- DME control module faulty

Affected terminals
Connector A, pin 80

Diagnosis/troubleshooting

NOTE:
- The fuel tank leak test for the Cayenne is carried out with approx. 20 mbar overpressure in the tank. This overpressure is built up by the leakage diagnosis pump and is evaluated using an integrated reed contact. The pump work is performed by a spring, which is stretched via a diaphragm by the vacuum from the intake manifold (or supply tank).
- The diagnostic conditions can also be 'forced' by performing the "Leakage Diagnosis" short test using the 9588 Porsche System Tester II.
- The reed switch in the leakage diagnosis pump is checked before the actual tank leak test is performed. If the reed switch is in an implausible position (in this case: closed) after the start of the test (generating a vacuum in the pump), the fault is entered and the tank leak test is aborted.

DANGER:
- Danger of poisoning through petrol.
- Inhaling vapours can lead to irritation of the mucous membranes and eyes.
- It represents a serious risk to health when inhaled, touched or swallowed over longer periods.
- Wear a breathing mask with active charcoal filter; do not breathe in any fuel vapours.
- Wear protective gloves that are fuel resistant.
- Only work on the fuel system in well-ventilated locations.
- Before opening fuel lines or fuel hoses, relieve the fuel pressure.
- Collect escaping fuel; absorb it if necessary with a suitable binding material and dispose of properly
- Pay attention to cleanliness when working on the fuel system.

DANGER:
- Risk of fire and explosion when handling petrol.
- Keep clear of ignition sources.
- Do not smoke.
- Do not carry out welding or grinding work in the immediate vicinity (naked flame and flying sparks).
- Prevent escaping fuel from coming into contact with hot engine components.
- Avoid electric discharges in the vicinity of escaped fuel.
- Secure the vehicle, e.g. with a warning sign.
- Change any clothing soaked with fuel immediately.
- In the event of a tire, use C02 or dry powder tire extinguishers.






1 - Vacuum line disconnection point between vacuum accumulator in intake manifold and leakage diagnosis pump
2 - Purge air line disconnection point between active charcoal filter and EVAP canister purge valve
3 - Fuel supply line disconnection point

9160/1 Mityvac II vacuum tester with pressure gauge






Evaporative Emission System Leak Detection Pump Sense Circuit Range/performance