Powertrain, generic (extended)

P22B5 O2 Sensor Pumping Current Trim Circuit/Open (Bank 1 Sensor 2)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P22B5 flags an open trim line on the bank 1 downstream wide-band probe. Bosch LSU probes carry a trimming resistor in the connector module, wired to pin 5 (RT/IA), that sets each sensor's individual characteristic; the controller reads it to scale the measured pump current. Lose that line and the oxygen value can still move, but with the wrong gain. Chrysler's wording speaks of the pump cell current trim of sensor 1/2 and lists the code for 2010-2012 Ram 2500/3500 with the 6.7 Cummins; after the wiring repair its road test compares both sensors during 10-second fuel cut-offs and allows no more than 4 % difference. Saab's upstream analog P2626 is checked in overrun below 750 °C and sets above 4.81 V. P22B6/P22B7 are low/high, P22C2 bank 2.

Likely causes

Corroded or loose trim-line terminal in the sensor connector
Trim wire broken between sensor connector and ECM or sensor module
Open trimming resistor in the sensor's connector module

Symptoms

  • Check engine light
  • Downstream oxygen reading disagrees with the upstream sensor during fuel cut-off
  • Follow-up aftertreatment or catalyst faults possible

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 bank1 sensor2oxygen sensor wiringecm

Related codes

P22B6P22B7P22C2P2626P22AB

References: static.nhtsa.gov, static.nhtsa.gov, bosch-motorsport.com, saabwisonline.com.