Check engine light came on..Took it to the mechanic and after running diagnostic, he replaced the O2 sensor and turned off check engine light. I drove the car for 100 miles and then went back to mechanic. The O2 sensor now shows as OK, but Catalytic Convertor shows as NC and the light came back on. The code is now P0135. What to do?? I appreciate your help!

 

welcome to the forum. if the mechanic used an after market 02 sensor and not a honda sensor it may be the sensor bad. If the sensor is a honda sensor, then it could be a cat. my 07 Fit cat went bad at 230k miles.