Circuit/System Description
WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.
This DTC tests the evaporative emission (EVAP) system for a restricted or blocked EVAP vent path. There are two parts to this test.
- Part one uses the fuel tank pressure sensor to indicate vacuum comes within a calibrated range within a calibrated time.
- The second part of this test looks for excessive vacuum which would indicate a restriction. The duration of this second part of is a function of purge volume through the system.
The following table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states of the EVAP purge and vent solenoid valves.
| ECM Command | EVAP Purge Solenoid Valve | EVAP Vent Solenoid Valve |
|---|---|---|
| ON | Open | Closed, Not Venting |
| OFF | Closed | Open, Venting |