Powertrain, generic (extended)

P22C4 O2 Sensor Pumping Current Trim Circuit High (Bank 2 Sensor 2)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P22C4 is the high fault on the trim circuit of the bank 2 downstream wide-band probe. In Ford's key-on check of NTK label resistors, an estimated resistance that is too low means the line is shorted to power, which sets the trim-high code (P2631 for the bank 2 front probe); the stored resistor rank then stays in use. On Bosch-type probes a raised trim voltage looks much like an open: Saab and VW both trip their front trim code above 4.81 V, so makers may sort this fault into the open-circuit code. No maker documents P22C4 publicly, and GM's bank 1 slot P22B7 serves a NOx sensor oxygen ceiling with no bank 2 counterpart. Typical causes are a short to the heater feed or a damaged plug. P22C2 is the open, P22C3 the low case. The lamp lights.

Likely causes

Trim wire shorted to the heater supply or another positive feed
Heat- or water-damaged sensor plug bridging the trim pin
Internally shorted label resistor in the sensor connector

Symptoms

  • Check engine light
  • Bank 2 downstream lambda slightly off; heater codes may accompany it

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

P22C2P22C3P22B7P2631

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