Powertrain, generic · Fuel and air metering

P0161 O2 Sensor Heater Circuit Bank 2 Sensor 2

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

The downstream oxygen sensor on bank 2 (sensor 2) has an electric heater so that it reaches working temperature quickly. P0161 concerns this heater circuit and its performance. GM measures the current through its low-side driver and fails it outside 0.3–2.9 A on the supercharged V8 (8 of 10 samples, two trips). Ford checks the driver voltage continuously and the current once per drive cycle once the sensor is estimated above about 120 °C; the lower limit is 0.22–0.55 A depending on sensor type, the upper 3 A. Without heat the sensor becomes active late or not at all, so P0159/P0160 can follow; there is no limp mode.

Likely causes

Heater element of the sensor burnt out
Heater wiring, connector or fuse open or corroded
Short in the heater circuit (current too high)
Driver in the engine module faulty

Symptoms

  • Check engine light on (usually after two drive cycles)
  • Follow-up codes P0159/P0160 possible
  • Catalyst monitor readiness for bank 2 not set

Repair estimate

DifficultyEasyDIY possible
Parts and labour€60–250
Time0.3–1.5 h

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

Parts involved

oxygen sensor heater bank2 sensor2oxygen sensor heater circuitfuses

Related codes

P0141P0056P0057P0058P0060P0167

References: law.cornell.edu, gsi.ext.gm.com, newtonnet.co.uk, fordservicecontent.com.