2000 Montana P0135 code

[gt4ms]

This code(P0135) just came up on my vehicle.Any idea what it refers to and how to fix? TIA. Said O2 Heater Circuit(bank 1,Sensor 1).

[dewaynep]

Yep, O2 sensor heater circuit malfunction. Most likely cause is bad O2 sensor. Could check on a good scan tool or just replace the O2 sensor.