Reduced Power and Park Assist During
 

I have a 2020 ES 350. I maintain the car well and have never had issues.

It snowed in WA State and it’s about 20 degrees, which is not common here. Few days a year, but it’s never usually this cold. Drove to store which is about 25 mins away. In total about 50 mins. I drove slow since it’s icy. When I was almost to store, the check engine light came on saying reduced engine power and break assist. My speed was steady though, but as I said, I was only doing between 25 and 30 mph since it was icy. I tried to speed up and it seemed ok. It drove ok, but seemed a little off more than normal. I’m positive it’s due to the cold weather. When I brake, there’s a slight tug which isn’t normal. Drove it home fine and it’s now parked. Attempted to turn off and on and still comes on. Any suggestions? I have to drive a long trip tomorrow and not sure what to do. It drives ok but as I said, I can something is off but it’s so minor that it’s hard to tell. Plus I’m a girl so what do I know lol

Multiple warning lights came on at once. Maintenance light, check engine light, the park assist said it was no longer available, that little lane symbol turned on too. I was reading car threads for other cars, and similar problems during cold temps.

It is very hard to guess without scanning the codes.
I suppose it has to do with the accumulated snow/ice on the front shutters.

It sounds like "limp" mode. Using a code scanner like Carista or a high end ($600 plus) should give you some codes. A $75 reader just doesn't speak enough Lexus to be more than partially helpful. Get to a Lexus savvy shop or a dealer.

Maybe your battery has a failing cell. Extreme cold is hell on a car battery if a few years old.

if still under warranty, take the car into dealer early in morning and get a loaner for your trip. You don’t want to be stranded away from home or on highway or in bad weather. Worst case, just a rent a car for the trip and worry about Lexus later in the day for repair next day. Don’t take a risk driving that car a distance, especially in this weather.

Even if it isn't under warranty, following Shaboom's advice is the best course of action.

Your ES 350 shouldn't be displaying such warning lights, especially the check engine light, in 20˚F temperatures. There's quite a few forum participants who live in US and Canadian locations where winter temperatures of 20˚F and lower are a pretty normal occurrence and they aren't experiencing the type of problems with their ESs that you're reporting.

Absolutely. Pardon my misstatement. Get it to your dealership for sure if under warranty. If not under warranty, then to dealership or your independent mechanic, as you prefer.

@Jas4654 Please post back when you find the problem. I'm betting @jimbosr1 is is onto something with the battery.