Powertrain, generic (extended)

P22BC O2 Sensor Reference Voltage Performance (Bank 2 Sensor 2)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P22BC concerns the plausibility of the Nernst-cell signal of the wide-band probe fitted after the bank 2 catalyst. The leads test fine, yet the cell voltage that the controller uses as its set point drifts, reacts slowly or cannot be held, so the computed oxygen value loses credibility. No maker documents this code publicly, and none publishes a limit for its upstream relative P2248 either. The usual reasons are physical: an aged cell whose resistance has climbed well above the nominal 300 ohms of a Bosch LSU 4.9, deposits from oil or coolant, or a weak heater. CARB requires a downstream sensor to remain good enough to judge the catalyst. Siblings: P22BB open, P22BD/P22BE low/high, P22AF bank 1. The lamp lights and catalyst results may be withheld.

Likely causes

Aged downstream wide-band sensor on bank 2 with raised Nernst-cell resistance
Oil, coolant or additive deposits on the sensing element
Heater output too low to keep the cell at working temperature
Contact resistance in the Nernst-cell terminal

Symptoms

  • Check engine light
  • Bank 2 downstream oxygen reading lags behind or is offset from the other sensors
  • Catalyst monitor for bank 2 does not complete

Repair estimate

DifficultyMediumDIY possible
Parts and labour€80–450
Time0.5–2 h

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

Parts involved

oxygen sensor bank2 sensor2oxygen sensor wiringecm

Related codes

P22BBP22BDP22BEP22AFP2248

References: law.cornell.edu, bosch-motorsport.com.