Vehicle engine controlling method, involves carrying out sulphur poisoning diagnosis of oxide trap, if sulphur purging conditions such as value for diagnosing fault of oxide trap is higher than sum of threshold and margin, are satisfied

摘要

The method involves performing a sulphur poisoning diagnosis of a nitrogen oxide trap, if sulphur purging conditions are satisfied. Conditions to be satisfied include a distance traveled by a vehicle, quantity of nitrogen oxide purges and time taken for purging sulphur contained in the trap, from functioning of the purge, are lower than respective preset values, and a preset criteria value for diagnosing a fault of the oxide trap is higher than sum of a fault informing unit activation threshold and a margin. The unit informs the fault to a driver of the vehicle.