Highlander knock sensor malfunction

Knock sensor issues on Highlanders are not unheard of. I've seen it before. Was the code specific to one sensor, or did it just say 'knock sensor malfunction'? Have you checked the sensor's resistance? A faulty sensor can trigger those symptoms.

The code was just a general knock sensor malfunction, not specific to a particular sensor. I haven't checked the resistance yet; I wasn't sure what the acceptable range should be. Is it possible that a bad connection could cause this even if the sensor itself is okay?

Yes, a bad connection is a common cause, especially with age and corrosion. But since you're getting a general code and have already checked the visible parts of the wiring, the sensor itself is quite suspect. It might be worth checking the resistance as suggested. However, given the symptoms and error code, I'd suggest taking it to a trusted workshop and have a professional look at it. It's probably the best route forward.

Thanks for the input. I took it to a workshop. Turns out it was a defective cable/plug connection, just as you suspected! Repair cost me 95€. Appreciate the help!