Some customers of 2013–2017 Buick Encore and Chevrolet Trax models with an electric power steering system (RPO NJ1) may encounter difficulty steering during colder temperatures. This may be accompanied by a knocking and/or clicking sound. 

The condition may stem from water intrusion in the steering gear input shaft that is freezing and/or causing corrosion. To correct the problem, check for water and corrosion at the power steering gear pinion housing. Note that a small amount of rust (one or two spots) is normal. 

If water intrusion or more than a couple of rust spots are found, replace the intermediate steering shaft boots (seals) and the steering gear.

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Caption: Excessive corrosion on a steering gear input shaft can cause difficult steering.