Conditions For The Regular Diagnosis

• Conditions for cold start diagnosis not fulfilled during this driving cycle or cold start diagnosis indicated a leak.
• Diagnosis commenced more than 8 times during this driving cycle.
• Approved transition diagnosis of oxygen sensor 1.
• PWM ratio to purge valve exceeds 40% at some time during this driving cycle (can be fulfilled by revving the engine to 3000 RPM).
• Idling speed
• Car stationary for more than 5 s.
• Max. one change of status of the brake light switch.
• Additional fuel from purge is less than 7 % of the engine's fuel requirements.

If the diagnosis is interrupted, the vehicle speed must exceed 4 km/h (2.5 mph) on one occasion before the diagnosis can be restarted.

While a diagnosis is in progress, the purge valve PWM ratio is set to 15 % at the same time as the additional fuel from the purge is allowed to be 13 % of that required by the engine.

Fig 1: Illustration For Steps 1-6

Courtesy of SAAB-SCANIA OF AMERICA, INC.

1. Store reference value: - tank pressure
   Fig 2: Illustration For Steps 1-3

   Courtesy of SAAB-SCANIA OF AMERICA, INC.
2. 15 % PWM to purge valve. Close EVAP shut-off valve.
3. Reduce tank pressure by 0.6 kPa within 23 s.
4. Stop pressure reduction.
   Fig 3: Illustration For Steps 4-7

   Courtesy of SAAB-SCANIA OF AMERICA, INC.
5. Tank pressure increases more than 0.3 kPa during 9 s.
6. Revert to normal venting.
7. Fault criteria for evaporative emission fulfilled. Note that both  the cold start diagnosis and  the ordinary diagnosis must indicate leakage before a DTC is generated.