2023 GMC Terrain Problems: 5 Known Issues

On the 2018-2025 GMC Terrain, the 2018+ Terrain with the 1.5L turbocharged engine (LYX; LSD from 2023) experiences PCV (Positive Crankcase Ventilation) diaphragm failure inside the valve cover. The integrated PCV diaphragm tears, causing excessive crankcase pressure that forces oil into the intake manifold and intercooler. Symptoms include oily residue around the air intake and intercooler outlet pipe. In severe cases, excessive crankcase pressure also causes coolant intrusion into the combustion chamber. This is the same problem affecting the Chevrolet Equinox 1.5T of the same era.

On the 2018-2024 GMC Terrain, on the second-generation Terrain (2018+) with the turbocharged 1.5L LYX/LSD or 2.0L LTG engine, the air-to-air charge air cooler (intercooler) accumulates condensate from humid or rainy driving plus PCV-borne moisture. In cold ambient temperatures that water freezes inside the CAC core, restricting charge airflow. GM documents this in service bulletin 18-NA-020, first released in January 2018 and later expanded through the 2024 model year. Owners on the Terrain/Equinox forum describe ice and standing water inside the charge tube. Here the cooler itself is blocked by ice or contamination; the duct has not come off the throttle body.

On the 2023 GMC Terrain, gM recalled 2023 Terrain vehicles built with ventilated front passenger seats because the Occupant Classification System may fail to properly disable the front passenger airbag when a small child or a child restraint is detected in that seat. If the airbag deploys against a child or a rear-facing child seat it can cause serious or fatal injury. The defect is specific to the ventilated-seat option. Terrains without ventilated front passenger seats are not included.

On the 2020-2023 GMC Terrain, gM recalled 2020-2023 Terrain vehicles because excessive powder coating on the four rear-seat lower child seat LATCH anchorage bars can prevent a child restraint from being properly installed or securely latched. A child seat that will not seat fully on the anchor may not restrain the child in a crash. This is a manufacturing/finish defect on the anchor bars themselves rather than a structural failure, and it is invisible to most owners until they actually try to install a LATCH-attached seat and cannot get a positive click.

On the 2010-2024 GMC Terrain, terrain front and rear hub assemblies integrate the ABS magnetic encoder ring into the bearing's inboard seal, where it sits directly exposed to road salt and moisture. Two distinct failure modes result. The mechanical one is the familiar humming or roaring that rises with speed and changes when loading the bearing in a wide turn. The one that fools owners and shops is encoder-ring failure on a bearing that is still mechanically tight and silent: the wheel speed signal drops out and the vehicle sets a wheel speed sensor code with ABS, traction control and stability control disabled. Replacing only the external sensor does not fix it, because the encoder is part of the bearing. Both generations are affected, with salt-belt vehicles failing earliest.