Unecessary shit co again syndrome again, did you put in a new CTS, there is NO need for high co, not when it's got a decent map anyway.
Mine read on the last mot 0.97% CO, 137ppm, running greys/T34.48 etc, with nearly 200,000 miles on the engine, bores were so worn it nearly jumped the 1st oversize, and I had piston slap when hot and warmed up all the time.
I would in any even put in a new cts, then recheck settings, it's not a million miles away from a pass, as said no doubt just needs a slight tweak.
tabetha