Powertrain, generic (extended)

P22A2 NOx Sensor Circuit Intermittent (Bank 1 Sensor 2)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P22A2 describes a rear NOx sensor on bank 1 whose measuring circuit reports faults that come and go rather than staying present. Smart NOx sensors pass the state of that circuit (open wire, short or no error) to the engine computer over CAN, so brief, repeated fault reports fit this code. No manufacturer publicly documents a threshold for P22A2. The only trace is a Ford notice for 2015 to 2016 6.7L Super Duty trucks (SSM 45920, NHTSA index only) explaining that the code may stay stored after the actual fault has been repaired; CARB requires NOx sensors to be monitored continuously for circuit faults. Look for loose terminals, heat-damaged cable along the exhaust and water in the connector. P229E is the steady fault, P2204 the same pattern at the front sensor.

Likely causes

Loose or corroded terminals at the outlet NOx sensor connector
Harness along the exhaust damaged by heat or vibration
Sporadic internal fault in the sensor module

Symptoms

  • Malfunction indicator lamp that may go out and return
  • Downstream NOx value dropping out briefly
  • Code remains stored after the root fault is fixed

Repair estimate

DifficultyMediumDIY possible
Parts and labour€50–900
Time0.5–3 h

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

Parts involved

nox sensornox sensor wiring

Related codes

P229EP22A0P22A1P2204U029E

References: law.cornell.edu, ni.com, hella.com.