Powertrain, generic (extended)

P2232 O2 Sensor Signal Circuit Shorted to Heater Circuit (Bank 1 Sensor 2)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P2232 reports that the heater supply of the oxygen sensor behind the catalyst on bank 1 is bleeding into that sensor's signal line. A switching sensor only produces up to about 1 V, so the ECM watches its signal at the instant the heater is switched off. GM's tables for the 2005 2.8/3.6 V6, the 2008 3.6 LLT and the 2024 set 24OBDG07 flag a jump of more than 2 V within 0.04 s of heater turn-off in more than 4 out of 6 events, with the MIL after two trips. The Saab 9-5 (2010, 2.0 turbo) checks whether signal and heater voltage rise and fall together and treats the fault as Type B. P2231 is the front sensor, P2235 the rear position on bank 2. Mixture control continues, but catalyst monitoring loses its rear signal.

Likely causes

Internal leakage between heater and sensing element of the rear oxygen sensor
Signal and heater wires fused or chafed together near the exhaust
Water or corrosion bridging pins in the sensor connector

Symptoms

  • Check engine light after two drives
  • Catalyst monitor not completed or catalyst code stored alongside

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 sensor2oxygen sensor heateroxygen sensor wiring

Related codes

P2231P2233P2235P0036P0137P0138

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com, saabwisonline.com.