P0166 O2 Sensor Circuit No Activity Detected Bank 2 Sensor 3

Sensor 3 on bank 2 is a switching oxygen sensor behind a second converter or converter brick. It is rare – documented for Jaguar Land Rover's supercharged V6 and V8 (2013–2016), where it is the 'post-cat' sensor of the second bank, and for Ford systems that monitor part of the converter volume. P0166 means sensor 3 shows no voltage change or stays in the control module's bias band – an open or high-resistance circuit, or a cold or dead sensor. For downstream sensor 2 GM sets the equivalent code when the voltage does not change after heater warm-up (within 15 s) or sits at 401–548 mV. No manufacturer document using exactly this code was found; Jaguar Land Rover does not list it and Ford uses only heater codes for sensor 3. A failed heater (P0167) can cause it. When it fails, the downstream evaluation of that converter is suspended; there is no limp mode.

Likely causes

Symptoms

• Check engine light on (usually after two drive cycles)
• Often together with P0167
• Usually no noticeable change in driving

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: law.cornell.edu, saabwisonline.com, saabwisonline.com.