Powertrain, generic (extended)

P2204 NOx Sensor Circuit Intermittent (Bank 1 Sensor 1)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2204 describes an upstream NOx sensor on bank 1 whose signal path works most of the time but keeps dropping out. Smart NOx sensors report the state of their measuring circuit (open wire, short or no error) to the engine computer over CAN; when such fault messages come and go faster than a steady circuit fault would allow, this code fits. No manufacturer publicly documents thresholds for P2204, so the logic is calibration-specific; CARB generally requires continuous detection of circuit-continuity faults on NOx sensors. Look for loose pins, heat-damaged cable near the exhaust and water in the connector. P2200 is the steady circuit fault, P2202/P2203 a value out of range. Expect a MIL and SCR warnings that may disappear and return.

Likely causes

Loose or corroded terminals at the NOx sensor connector
Harness near the exhaust damaged by heat or vibration
Intermittent internal fault in the sensor module

Symptoms

  • Malfunction indicator lamp on, sometimes going out again
  • NOx value in live data dropping out briefly
  • SCR warning that comes and goes

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

P2200P2202P2203P2212P2217

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