P0155 - O2 Sensor Heater Circuit (Bank 2 Sensor 1)

System Information

The heater circuit on a heated Oxygen / Lambda sensor is used to provide the heat required for correct sensor operation after cold start and also to maintain a consistent temperature during certain running conditions.
The heater circuit supply voltage can either be directly supplied from the ECM or it can be supplied via a relay, this would usually be the main system relay. The heater earth circuit will normally be controlled directly by the ECM

Fault Code Explained

This fault code indicates that the ECM has detected a fault in the heater circuit, this may be due to a fault with the supply voltage, the earth circuit or with the sensor itself. This fault code is normally set due to an undefined fault

The fault code is commonly set for the following reasons:

Recommended Tests

Different sensor types and wiring configurations are possible and it is recommended to refer to the manufacturers wiring diagram.

Test should include