P0449 Equinox: Troubleshooting the Vent Solenoid Control Circuit

Understanding P0449 Equinox: EVAP Vent Solenoid Control Circuit

A P0449 Evaporative Emission (EVAP) Vent Solenoid Control Circuit means there’s a problem with the vent solenoid or the circuit to the solenoid. Don’t just assume that you have a bad vent solenoid. Check the circuit first. Here’s how

P0449 Circuit Description

Battery voltage is applied to the EVAP emissions (for more information on EVAP systems, read this post) charcoal canister vent solenoid valve. When the ECM conducts a purge cycle to remove gas vapors from the charcoal canister, the ECM grounds the vent solenoid valve.

With the ignition OFF, disconnect the harness

Equinox P0449 Vent solenoid wiring diagram

connector at the vent solenoid valve (see diagram below. Then turn the IGN to ON. Check for battery voltage on terminal A in the connector (red/white wire). If you don’t see battery voltage on terminal A, check for blown F24UA 10A fuse in the underhood fuse box. If the fuse is good, check for a short to ground or an open/high resistance between the connector and the underhood fuse box. Some shops are reporting wiring issues on the power side of the circuit near the vent solenoid connector. Repair wiring issues before proceeding.

The shop manual then calls for activating the vent valve

AC Delco 22865590 vent solenoid

using a bi-direction scan tool to check for ECM provided ground on the B terminal in the connector. If the test shows ECM grounding, then the problem is a bad vent solenoid valve. Replace it. It’s located on the charcoal canister.

Vent solenoid location Equinox

©, 2018 Rick Muscoplat