Buick

The P0299 guide follows GM’s icing bulletins for temperatures at or below 0°F (−18°C). For the 1.4L LUV, 16-NA-405 covers ice in the PCV bypass, intake passages and charge-air cooler. For the LE2, 17-NA-221 covers thawing and cooler checks, moisture in the turbocharger control valve, and a new ECM calibration for the 2018, 2019 and 2021 model years only. That update changes cold-weather shifting, so highway engine speed can be higher.

The P1101 guide splits by engine. For the LUJ and LUV, GM’s preliminary information points to a PCV pipe whose valve stays open (PI0907C) and to a cam-cover or manifold PCV fault (PIP5197F). For the LE2, bulletin 20-NA-047 points to a blocked PCV orifice that raises crankcase pressure.

Identify the engine before reading either guide. GM lists the LUV in Encore tables as late as 2021 and the LE2 from 2016, so the model year alone does not settle it. Confirm the engine RPO or the VIN, then follow the matching branch.