This bulletin applies to 2017-2019 Chevy Cruze, 2018-2019 Equinox and GMC Terrain vehicles, equipped with a 1.6L turbo diesel engine. You may encounter a concern where the engine cooling fan is running, making a ratcheting, squeak, chirp, moan, whine and/or buzz type noise heard shortly after the engine has been turned off.
There are some components that may produce noises shortly after engine off:
1. The intake manifold runner control valve actuator may be heard cycling under the hood. This is done as an integrity check and to confirm that the mechanical link between the actuator and intake manifold runner is still connected.
2. The diesel exhaust fluid (DEF) pump and DEF reverting valve purging DEF. The DEF pump and DEF reverting valve may be heard from the right rear of the vehicle. When the engine is turned off, the DEF pump and reverting valve operate to relieve the DEF system pressure and to clear the lines of DEF. The reverting valve is opened to relieve pressure and send the fluid back to the DEF tank, and then the valve is closed once the DEF lines are clear.
3. When the engine is shut off while a particulate filter cleaning process is active, the cooling fan will run for two minutes to cool the particulate filter. The cooling fan running after shut-down may be accompanied by a hot odor.
These noises are considered to be normal operating characteristics.