Powertrain, generic (extended)

P2231 O2 Sensor Signal Circuit Shorted to Heater Circuit (Bank 1 Sensor 1)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2231 means the engine computer sees the heater supply of the upstream oxygen sensor on bank 1 leaking into the sensor's signal path - typically an internal short in the sensor or two neighbouring wires touching in the harness. VW's 2014 specification books for the Passat and Tiguan set it when the front sensor signal changes by more than 190 microamps, i.e. the measured sensor current is distorted. CARB requires circuit faults of every fuel-control oxygen sensor to be detected. P2232/P2233 cover sensors 2 and 3 of bank 1, P2234 the first sensor of bank 2. Because the mixture feedback can no longer be trusted, the engine may run on open-loop fuelling with higher consumption and emissions.

Likely causes

Internal short between heater and sensing element in the oxygen sensor
Heater and signal wires melted or chafed together (exhaust heat, routing)
Moisture or contamination bridging pins in the sensor connector

Symptoms

  • Check engine light
  • Higher fuel consumption due to open-loop fuelling
  • Rough idle or hesitation in some cases

Repair estimate

DifficultyMediumDIY possible
Parts and labour€80–350
Time0.5–1.5 h

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

Parts involved

oxygen sensor bank1 sensor1oxygen sensor heateroxygen sensor wiring

Related codes

P2232P2233P2234P0030P0130

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov.