Powertrain, generic (extended)

P2272 O2 Sensor Signal Biased/Stuck Lean (Bank 2, Sensor 2)

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

P2272 applies to V and flat engines with a separate catalyst and rear oxygen sensor on bank 2; that sensor fails to reach a rich reading when the ECM enriches bank 2. GM's 2016 tables (16OBDG05) set it if the voltage is still under 800 mV after 68 g of air during forced enrichment (Type B). GM's Bosch-based 2005 2.8 and 3.6 V6 first wait for 100 s below about 0.58 to 0.66 V, then ramp up the fuel and fail the sensor if it has not risen 10 s after the enrichment limit. Ford uses the same 0.42 V limit as on bank 1. Mazda found oil from a leaking oil pressure switch inside connector C-34 on the 2007 to 2015 CX-9, stored with P2A04, and fixed it with a new switch and a cleaned connector. If only bank 2 reports a fault, comparing its data with bank 1 narrows it down.

Likely causes

Bank 2 rear oxygen sensor aged or contaminated

Engine oil in the sensor connector, for example from a leaking oil pressure switch

Exhaust leak on bank 2 ahead of the rear sensor

Symptoms

Malfunction indicator lamp on
Catalyst monitor for bank 2 not completing

Repair estimate

DifficultyMediumDIY possible

Parts and labour€0–300

Time0.3–2 h

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

Parts involved

oxygen sensor downstreamoxygen sensor wiringcatalytic converter

References: gsi.ext.gm.com, gsi.ext.gm.com, newtonnet.co.uk, static.nhtsa.gov.