Lexus IS rough idle defective plug

Rough idling and error codes could point to a few things. Did you check the cable and plug connections? A loose or corroded connection to the engine mount sensor can throw things off. It's a simple check before replacing parts.

Good point about the connections! I didn't think of that. Is there a specific connector I should be looking for near the motor mount, or elsewhere on the engine? Any tips on what to look for when checking it?

It's usually near the engine mount itself. Look for any damage to the cable, or corrosion on the plug. Give it a wiggle and see if anything changes. But honestly, with those symptoms, get it to a shop; could save you money in the long run.

Thanks for the help! The connection was the issue. The shop found a defective plug connection to the engine mount. 95€ later, and it's running smooth!