P0145 O2 Sensor Circuit Slow Response Bank 1 Sensor 3

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. P0145 means sensor 3 reacts too slowly to mixture changes, typically measured around fuel cut-off as for sensor 2 (P0139). No manufacturer document using exactly this code was found – Jaguar Land Rover, the only documented user of sensor 3, does not list it. The description rests on CARB's response-rate requirement for downstream sensors and on the sensor 2 test logic. When it fails, the control module stops the downstream trim and cannot evaluate the converter; there is no limp mode.

Likely causes

Symptoms

• Check engine light on (usually after two drive cycles)
• 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, newtonnet.co.uk.