P0146: O2 Sensor Circuit No Activity Detected Bank 1 Sensor 3

What does P0146 mean?

Sensor 3 is a third oxygen sensor on bank 1, behind a second converter or converter brick. It only exists on some vehicles – documented for Jaguar Land Rover's 3.0 V6 supercharged (2013–2016, where sensor 2 is 'mid-cat' and sensor 3 'post-cat') and Ford systems that monitor part of the converter volume. P0146 means sensor 3 produces no voltage of its own and only the control module's bias voltage is seen, as for sensor 2 (P0140): GM evaluates a signal stuck in the 401–548 mV band, a high internal resistance or, with 1900 mV bias, an open circuit. No manufacturer document using exactly this code was found; Jaguar Land Rover lists only P0142–P0144 and P0147 for its sensor 3. When it fails, the control module stops the downstream trim and cannot evaluate the converter; there is no limp mode.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light on (usually after two drive cycles)
• Usually no noticeable change in driving

Common causes

• High Signal or ground wire open, connector off or corroded
• Medium Sensor heater failed, sensor never becomes active
• Medium Sensor worn out (no longer produces voltage)

Likelihood is a general estimate across vehicles; your make and model may differ.