2002 Toyota Camry LE 2.4 A/T 85k miles. all maintenance up to date.
I got a CEL P0420 last night, car ran fine for 85 miles back to house. Hook scan tool up to look at sensor outputs, and found that the A/F ratio sensor is N/A. And that the car is never going into open loop. Coolant temp stays around 185 at 55 mph and will only hit 200 if I hold it at around 2500 RPM in neutral while stopped. Even on the highway it stays in closed loop. I know about the P0420 catalyst code every Camry I have ever had eventually gets it. Last 2 Camry’s needed downstream O2 sensors 1 Camry got totaled before i resolved the P0420. But could it be caused by staying in closed loop for extended periods of time? Should I replace the thermostat to try to get the engine temp up? Any ideas?