P019B O2 Sensor Delayed Response - Lean to Rich Bank 1 Sensor 3

Sensor 3 on bank 1 is a switching oxygen sensor behind a second converter or converter brick; it exists on Jaguar Land Rover's supercharged V6 and V8 (on both banks) and on Ford systems that monitor part of the converter volume. 'Delayed response' means the sensor starts reacting too late after a mixture change – unlike 'slow response' (P0145/P0165), where the transition itself is too flat. This code covers the lean-to-rich direction, tested when the module enriches the mixture after overrun. For sensor 2, GM checks whether the signal rises above 350 mV before a calibrated air mass has passed; behind two converters their oxygen storage buffers the change, so limits are wide. No manufacturer document using exactly this code was found – the Jaguar Land Rover bulletins list only P0142ff/P0162ff for sensor 3 – so the description rests on CARB's response requirement and the sensor 2 logic. There is no limp mode; the converter monitor cannot complete.

Likely causes

Symptoms

• Check engine light on
• No noticeable change in driving
• Catalyst readiness not set (emissions test)

Repair estimate

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

Parts involved

Related codes

References: law.cornell.edu, gsi.ext.gm.com, static.nhtsa.gov, static.nhtsa.gov.