P0155

Schematic:

The front oxygen sensors are equipped with heaters to assist in ramping up to the nominal operating temperature of the front oxygen sensors which is 750°C (1382°F). This decreases the amount of time required to enter closed-loop operation where maximum fuel efficiency is attained. The ECM diagnoses the heater and it's related wiring by continuously monitoring electrical current. The ECM will set this DTC if the O2 sensor does not become active within 20 seconds of the heater reaching 37°C (99°F).

DTC PARAMETERS
This DTC will set when:
^ Battery voltage is not between 11.03 and 15.52 volts
^ Engine is running
^ 20 Seconds has elapsed since heater reached closed-loop temperature

DTC P0155 is a (type B) DTC

DIAGNOSTIC AIDS
DTC P0155 is a rationale check on the heater circuit of HO2S bank 2 sensor 1. This DTC is the result of an inactive sensor 20 seconds after the sensor has reached operating temperature. The ECM will only run this rationale check if heater has passed the low and high fault circuit tests.

Possible causes:
^ Exhaust leak near HO2S bank 2 sensor 1
^ Contaminated sensor or slow sensor

NOTE: If P0154 is also set, a signal circuit problem exists and should be diagnosed first.