My Tacoma engine light popped on out of the blue. Advance Auto did a free diagnostic that IDed the “Bank 2 O2 sensor” as the probable culprit.
So I took it to a trusted mechanic who discovered several vacuum hoses chewed thru by rodents. O2 sensor was good. $10 parts, $100 labor .. and a free tip.
He told me to spray all rubber hoses and components under the hood with peppermint oil. So I bought the concentrate at Home Depot, mixed with water per the instrx, and sprayed that shit all over every rubber hose/connection I could see. I respray monthly assuming it loses potency.
Another tip. Generac maintenance guy told me mice and ants are tough on generator wiring and electronics. He told me to set a bag of mothballs on the battery and to put a fresh bag in at each annual service. I also put a bag on my John Deere mower’s battery after a rat jumped from under the hood when I opened it to check the oil.
Anyhow, if rodents are the problem …