P2277 O2 Sensor Signal Biased/Stuck Rich (Bank 2, Sensor 3)

P2277 is the rich-side counterpart of P2276: the third, post-catalyst sensor on bank 2 does not drop to a lean reading. On such layouts the check normally runs during a fuel cut, when the second catalyst must fill with oxygen before the sensor can respond, so a slow or fouled element shows up here. No manufacturer publishes a threshold for P2277 itself; Jaguar Land Rover lists it among the bank 2 post-catalyst sensor codes of the 2014 to 2016 3.0 supercharged V6 and replaces water-damaged sensors. For reference, VW tests the bank 1 twin P2275 against 0.15 V after 4500 mg of oxygen, and Ford fails a sensor whose lean peak never drops below 0.48 V. A shorted signal wire or oil and coolant fouling are further causes. P2273 is the fault at sensor 2; P0164 a voltage above range.

Likely causes

Symptoms

• Malfunction indicator lamp on
• No noticeable change in driveability

Repair estimate

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

Parts involved

Related codes

References: static.nhtsa.gov, newtonnet.co.uk, static.nhtsa.gov, law.cornell.edu.