I had these codes after starting the engine. Was wondering should i go after the coolant sensor or the o2 sensor or something else. I've read some conflicting information about what would cause the issue. Some said the coolant sensor but ive read that the computer has a back up input for mixture scheduling. I have also read that the 02 sensor(post converter) is not used for mixture either. If this was a br710 on a gulfstream, i would have it wrapped up. Car engines tend to be more difficult to troubleshoot.