My car: 2018 Camry XSE with 104k miles.
The issue started while driving—out of nowhere, the check engine light came on, and I got an ICS malfunction warning.
I searched online but didn’t find much about it. There’s a YouTube video showing this exact problem where a mechanic explains the issue, but he didn’t show if the fix actually worked. I’m here to confirm that it does.
The fix: The mechanic diagnosed it as a bad downstream O2 sensor, which is under the car along the exhaust, right after the skid plate. I ordered a replacement online and swapped it out. After that, both warnings disappeared.
I wanted to share this in case anyone else runs into the same problem. I didn’t hook up a scanner to check the exact fault code, but I’d recommend doing that just to be sure.