I presently am receiving two error codes, 4-3-5 and 4-4-3, one which indicates that the O2 sensor is slow to respond, and the second, that the catalytic converter efficiency is poor. I recently experienced flooding problems during extreme cold conditions, and thus the above problems began. The 850 Turbo presently has 200,000 km thus the front O2 sensor definitely needs replacement, but would you suggest a gas line detergent to clean the catalytic converter? If so, can the cleaning product harm any other fule system components in the process?

Thanks...