Powertrain, generic (extended)

P22AD O2 Sensor Positive Current Control Circuit High (Bank 1 Sensor 2)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P22AD is the high-side fault on the positive current control line of the bank 1 downstream wide-band probe: the pump-current wire is pulled above its expected level, for example by contact with the heater feed or another supply wire. On Saab's 2010 9-5 the pump-current pins measure roughly 2.8 V at the plug, which gives a feel for the normal bias. GM lists the code in bulletin 21-NA-149 for the 3.0 Duramax LM2, again tied to engine harness chafing, but publishes no limit. Ford sends shorts to power on its upstream wide-band probes to P0132 instead of a dedicated code. The upstream analog is P2239 (Type B at Saab); P22AB is the open circuit, P22AC the low reading, P22BA the bank 2 version. The lamp is lit; driving normally feels unchanged.

Likely causes

Pump-current wire shorted to the heater supply or another positive feed
Internal short between heater and pump cell in the sensor
Faulty sensor interface in the ECM or sensor module

Symptoms

  • Check engine light
  • Downstream oxygen reading implausibly high or fixed
  • Readiness monitors for catalyst or aftertreatment not completed

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

P22ABP22ACP22BAP2239P22B4

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