On idle, my car has passed its test but on raised engine speed the CO level raises gradually from 0.479 to as high as 0.880 which is a fail. All other measurements remain within allowances. It has new plugs, lambda sensor and CAT. I also ran it on 98 octane with Inj. cleaner and rechecked it with an engine temperature at 100 deg. but no better. Diagnostics enquiry gives " either a lost connection to the ecu or a sensor not responding" result. Fat lot of good that is ( I have replaced the engine loom too). Anyone know what device would control this?