co emissions

HI

just had my jeep down to the m.o.t. testing station , failed on Co emissions! 0.46 i asked if i needed to renew o2 sensors or cat , he told me they were working fine ? and said to use a fuel treatment additive and suggested valvoline syn power gasoline system cleaner, and this would do the job. so taken his advice and going for a re test monday. has anyone used this or any other additive? jeep cherokee 1997 2.5 110.000 miles, .........thanx

I was told acetone or ethenol will work good for that.
acetone is 2 onces per 10 gallons, and you need to run it for a while.

found the problem , took the exhaust off today nothing inside the cat!! and the back silencer is rattling with bits inside,,,,,,,, going for new parts tomorrow.......cya

fitted new cat today , went for retest passed, co 0.01 ...........party1: ..............cya