Powertrain, generic (extended)

P2245 O2 Sensor Reference Voltage Circuit Low (Bank 1 Sensor 1)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2245 reports that the reference voltage side of the upstream air-fuel sensor on bank 1 reads too low, usually because the wire touches ground or the sensor has shorted internally. GM's tables for the Saturn Vue 3.5 V6 (L66, 2004-05) define it precisely: with the engine running for over 85 s, the heater active and the element signal between 3.2 and 4.6 V, a pump-cell circuit voltage below 1.5 V for 0.5 s stores the code in the first drive cycle. Jaguar Land Rover lists P2245 among the front-sensor codes in bulletin LTB00671 (2014-16 3.0 supercharged V6), where water caused thermal shock and the sensor is renewed. GM's 2018 Duramax table 18OBDG04 counts it among faults that invalidate the front sensor signal. P2243 is the open line, P2246 high, P2249 bank 2.

Likely causes

Reference voltage wire shorted to ground (chafed against exhaust or body)
Sensor element damaged internally, for example by water hitting the hot ceramic
Fault in the sensor interface of the ECM

Symptoms

  • Check engine light
  • Higher fuel consumption from open-loop fuelling on bank 1
  • Uneven idle or hesitation in some cases

Repair estimate

DifficultyMediumDIY possible
Parts and labour€80–450
Time0.5–2 h

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

Parts involved

oxygen sensor bank1 sensor1oxygen sensor wiringecm

Related codes

P2243P2244P2246P2249P2238P0131

References: gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov, gsi.ext.gm.com.