Q: My 2002 Honda Odyssey has a Check Engine light. It's supposed to be a misfire. The mechanic adjusted valves and changed coils but the issue remains

Hello. What problem code is stored for the Check Engine light? Hopefully all the plugs and all the coils were changed. If there was oil leaking (from the valve cover gasket) onto the plugs or rubber coil boots, this can cause shorting and a misfire. Unless a valve is burned, it’s unlikely a "bad head" is the cause of the misfire. A blown head gasket could cause a misfire - although other symptoms would be evident: overheating, loss of coolant, white smoke that smells sweet out of the tailpipe. If you would like a 2nd opinion, I would recommend having an engine is misfiring inspection completed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost for repairs.