Technical Description of OBD-II Trouble Code
Malfunction in the O2 Sensor Heater Circuit (Bank 2 Sensor 1)
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code that is applicable to vehicles equipped with OBD-II. Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
This code pertains to the front oxygen sensor on Bank 2. The heated circuit in the oxygen sensor reduces the time required to enter closed loop. When the O2 heater reaches its operating temperature, the oxygen sensor reacts by switching according to the oxygen content of the exhaust surrounding it.
The ECM keeps track of the time it takes for the oxygen sensor to start switching. If the ECM determines (based on coolant temperature) that too much time has passed before the oxygen sensor started functioning properly, it will set the P0155 code. See also: P0135 (Bank 1).
Potential Symptoms
You may notice poor fuel economy and the illumination of the MIL.
Causes
A code P0155 may indicate that one or more of the following issues have occurred:
