Enable criteria:
- Coolant Temperature when starting is between 5 -40°C. The difference between coolant temperature and intake air temperature is less then 5 °C.
If the above conditions are not fulfilled, Test 2 will start.
Idling speed. Max. one change of status of the brake light switch. Purging adaptation higher than -15%. Intake air pressure at least 20 kPa lower than the barometric pressure. Vehicle at a standstill for 5 seconds. The volume of fuel in tank between 9-54 litres. Battery voltage between 10 -16 volts. Tank pressure between -300 and +100 Pa.
When the above conditions are fulfilled for more than 5 sec. the diagnosis will start. Should the diagnosis be interrupted the speed must exceed 0 at one stage before the diagnosis is allowed to be restarted. The diagnosis is divided in three phases, A -C:
Phase A) Evaporation check The shut-off valve is activated (closed) at the same time as any purging is interrupted for 4.5 sec. The tank pressure is observed, decreasing pressure reveals a leaking canister purge valve. Increasing pressure by more than 3 Pa/s hints at fuel evaporation, in these cases Phase A should be repeated. If it then continues to rise by more than 3 Pa/s quit the diagnosis. To be able to continue, vehicle speed is required for a short time. When the pressure increases less then 3 Pa/s Phase A is complete. The diagnosis continues to Phase B (pressure decrease)
Phase B) Pressure decrease Shut-off valve is still closed, canister purge valve pulse ratio is set to 23 - 24.5% until the tank pressure has reached -600 Pa. This decrease in pressure should take Max. 30 sec.
Phase C) Maintaining pressure The shut-off valve is still closed, canister purge valve is closed. The tank pressure is observed for max. 12 sec.