Powertrain, generic · Hybrid propulsion

P0AC7 Hybrid/EV Battery Temperature Sensor B Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P0AC7 means the voltage of battery temperature sensor B is below its valid range. GM's sensors are NTC thermistors, so a low voltage equals an extremely hot reading, usually from a short to ground. The thresholds differ by program: the 2016 and 2019 tables fail it above 160 °C in 8 of 10 samples; the two-mode tables of 2011 and 2013 above 95 °C in 30 of 40 samples; GM's 2013 table 13OBDG05C below 0.3 V, about 90 °C, in 7 of 10. All are Type B, two trips. GM's Volt bulletin 18-NA-342 names P0AC7 among sensor codes that can set falsely and calls for a software update. A genuine hot pack would trip far lower thresholds first, so treat P0AC7 as an electrical fault.

Likely causes

Sensor B signal shorted to ground inside the pack harness
Thermistor shorted internally
Controller software setting the code falsely (Volt bulletin 18-NA-342)
Moisture or coolant at the sensing board connector

Symptoms

  • Check engine or hybrid warning light
  • Sensor B shows an implausibly high temperature
  • Charging and drive power reduced

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€60–2,500
Time0.5–5 h

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

Parts involved

hv battery temp sensor bwiring harnessbms

Related codes

P0AC8P0AC5P0AC6P0A9DP0ACC

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