Powertrain, generic (extended)

P2379 O2 Sensor Out of Range During Deceleration (Bank 2 Sensor 2)

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

P2379 covers the oxygen sensor behind the catalyst on bank 2 at the moment the injectors are shut off on a closed throttle: the exhaust is then close to fresh air, and a sensor whose reading stays outside the expected lean window is suspect. No manufacturer documents P2379 publicly. The nearest published logic is GM's bank 1 code P232F on the 2023 6.6L L5P, which compares the O2 value of the rear NOx sensor with the front one during overrun (window +3.01 to −3.18 %, Type B); that engine has no second bank. Ford checks the same sensor during fuel cut but reports under P013C, P014A or P2272/P2273. CARB asks at least for a rich-to-lean check of rear sensors in fuel shut-off. Code lists also give P239F this title. The car drives normally; the light points to sensor ageing or an exhaust leak.

Likely causes

Bank 2 downstream sensor aged or contaminated, reacting too little to fuel cut

Exhaust leak near the bank 2 rear sensor diluting or distorting the sample

Chafed sensor lead or corroded connector on the bank 2 rear sensor

Leaking injector on bank 2 keeping fuel in the exhaust during overrun

Symptoms

Check engine light on
No noticeable change in how the car drives
Downstream O2 reading on bank 2 stays high during coasting in live data

Repair estimate

DifficultyEasyDIY possible

Parts and labour€0–300

Time0.3–1.5 h

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

Parts involved

oxygen sensor b2s2exhaust after catalyst b2

References: law.cornell.edu, gsi.ext.gm.com, fordservicecontent.com.