Powertrain, generic (extended)

P2233 O2 Sensor Signal Circuit Shorted to Heater Circuit (Bank 1 Sensor 3)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P2233 is the heater-to-signal short for sensor 3 on bank 1, a third oxygen sensor that some engines fit after a second catalyst or between two catalyst bricks. No manufacturer documents this code publicly. GM's checks for the rear-sensor codes P2232/P2235 show how such a fault is normally caught: the signal leaps by more than 2 V within 0.04 s whenever the heater is switched off. Jaguar Land Rover's 2015 bulletin for the 3.0 supercharged V6, which carries three sensors per bank, lists many sensor 3 faults but none of this type. CARB requires circuit faults of every monitored oxygen sensor to be detected. P2236 is the bank 2 counterpart. A third sensor serves only monitoring, so the car drives normally with the warning lamp on.

Likely causes

Internal leakage between heater and sensing element of sensor 3
Sensor 3 wiring melted or chafed along the exhaust or underbody
Corroded underbody connector of the third sensor

Symptoms

  • Check engine light without noticeable driving change
  • Emissions inspection failed because of the stored code

Repair estimate

DifficultyMediumDIY possible
Parts and labour€60–280
Time0.4–1.5 h

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

Parts involved

oxygen sensor bank1 sensor3oxygen sensor heateroxygen sensor wiring

Related codes

P2232P2236P0042P0143P0144

References: law.cornell.edu, gsi.ext.gm.com, static.nhtsa.gov.