Tank Integrity Diagnosis

WARNING: This page is about a different car, the 2003 Saab 9-3. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Circuit Diagram (Tank Integrity Diagnosis)

Courtesy of SAAB-SCANIA OF AMERICA, INC.

A check that no leakage occurs in the evaporative emission system can be carried out by means of a tank integrity diagnosis. The leakage test involves creating a partial vacuum in the system and maintaining it for a given time during the diagnostic process.

The diagnostics logic has been improved to provide surer diagnosis. A diagnostic trouble code (DTC) will not be set until a negative result has been obtained from two tests during the same diagnostic process.

If there is leakage during one of the tests, SID will display the message "TIGHTEN FUEL FILLER CAP". This message is sent after each test if leakage is detected, but not more than twice in succession. After this, it is not possible to send the message again until the diagnosis from a test has reported OK.