Powertrain, generic (extended)

P22C2 O2 Sensor Pumping Current Trim Circuit/Open (Bank 2 Sensor 2)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P22C2 reports an open trim line on the bank 2 downstream wide-band probe. Every probe ships with a calibration resistor in its plug (pin 5, RT/IA on a Bosch LSU) that corrects for spread in its diffusion gap; on Bosch probes it sits in parallel with the controller's sense resistor. Ford explains that if it opens, all pump current is forced through that measuring resistor, tilting the lambda curve, a small error near stoichiometry. No maker documents P22C2 publicly. Upstream on bank 2 it is P2629: VW's 2014 Touareg triggers above 4.81 V, Saab tests P2626 during overrun below 750 C, and Ford bulletin 17-2124 replaces the front probes of the 3.5 GTDI for P2626/P2629. P22C3/P22C4 are low/high, P22B5 bank 1. The lamp lights.

Likely causes

Corroded or loose trim-resistor terminal in the sensor plug
Trim resistor or its lead open inside the sensor connector
Trim wire broken between connector and control module

Symptoms

  • Check engine light
  • Bank 2 downstream lambda reads slightly off, most visibly away from lambda 1

Repair estimate

DifficultyMediumDIY possible
Parts and labour€0–450
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

P22C3P22C4P22B5P2629

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