Outline Of Diagnosis

This diagnosis judges whether the leak check valve assembly operation is normal or not, and whether the evaporative emission system has leak and clogging or not.

To purge the canister, after driving, perform the five hours soaking after ignition switch OFF in order to stabilize the evaporative gas status. *After 5, 7 or 9.5 hours passed, ECM is activated by soaking timer, and the leak check starts.

Judges whether the leak check valve assembly operation is normal or not, by measuring the reference pressure status via reference orifice (0.02 inch orifice). Judge as malfunction if the reference pressure is out of specified range. Then, judge whether there is a leak or not, by comparing the pressure (leak pressure) when the reference pressure and the evaporative emission system are in negative pressure condition. Judge as system leak in the evaporative emission system if the leak pressure is higher than reference pressure. Judge as clogging of pipe if the leak pressure becomes lower than the reference pressure within the specified amount of time.

0.02 inch leak and 0.04 inch leak can be distinguished by measuring the leak pressure.

The diagnosis results are stored inside ECM until the engine is started again.

*: When the test conditions are not met in 5 hours, diagnosis is performed at elapsed time of 7 hours.

When the test conditions are not met in 7 hours, diagnosis is performed at elapsed time of 9.5 hours.

OUTLINE OF DIAGNOSIS

Courtesy of SUBARU OF AMERICA, INC.