Powertrain, generic (extended)

P22BB O2 Sensor Reference Voltage Circuit/Open (Bank 2 Sensor 2)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P22BB reports an open reference voltage line on the bank 2 downstream wide-band probe, meaning the controller has lost the Nernst-cell signal (RE/UN on Bosch, VS on NTK) it needs to regulate pump current and compute oxygen content. No maker documents this code publicly. For the upstream bank 2 relative P2247, Ford flags an open reference lead once the sensor voltage leaves 0.2-4.7 V for 10 s, and VW's 2014 Touareg data book calls the same fault an open Nernst voltage below 0.25 V or above 4.80 V with cell resistance over 950 ohms. Its bank 1 twin P22AE is listed by Chrysler for the 6.7 Cummins Ram. Only engines with two exhaust banks and a wide-band probe after each catalyst can set it. P22BC-P22BE are the performance/low/high siblings. The lamp comes on.

Likely causes

Corroded or loose Nernst-cell terminal in the connector
Reference wire broken in the harness
Cracked sensing cell or internal open in the sensor

Symptoms

  • Check engine light
  • Bank 2 downstream oxygen value invalid

Repair estimate

DifficultyMediumDIY possible
Parts and labour€0–450
Time0.5–2.5 h

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

Parts involved

oxygen sensor bank2 sensor2oxygen sensor wiringecm

Related codes

P22BCP22BDP22BEP22B8P22AEP2247

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