Powertrain, generic (extended)

P22B0 O2 Sensor Reference Voltage Circuit Low (Bank 1 Sensor 2)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P22B0 says the reference voltage (Nernst-cell) line of the bank 1 downstream wide-band probe sits below its permitted range. On a Bosch LSU the Nernst cell is a high-impedance source that tolerates at most about 250 microamps, so a chafed wire touching ground drags it down at once. No maker documents this exact code publicly. Ford's upstream logic treats a cell voltage under 0.2 V as part of its open-circuit check and books shorted leads under P0131, which shows that makers split these faults differently. JLR lists the upstream analog P2245 in a bulletin on cracked sensors. P22AE is the open case, P22B1 the high one, P22AF the performance check, P22BD the bank 2 equivalent. The driver mainly sees the warning lamp.

Likely causes

Nernst-cell wire shorted to ground through damaged insulation
Internal short in the downstream wide-band sensor
Moisture in the connector creating a leakage path

Symptoms

  • Check engine light
  • Downstream oxygen value implausible or unavailable

Repair estimate

DifficultyMediumDIY possible
Parts and labour€50–450
Time0.5–2.5 h

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

Parts involved

oxygen sensor bank1 sensor2oxygen sensor wiringecm

Related codes

P22AEP22AFP22B1P22BDP2245

References: static.nhtsa.gov, law.cornell.edu, bosch-motorsport.com, newtonnet.co.uk.