Powertrain, generic · Hybrid propulsion

P0BC9 Hybrid/EV Battery Pack Cooling Fan 1 Sense Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P0BC9 means the speed feedback of battery cooling fan 1 is implausibly low while the fan is running. GM evaluates the feedback as a frequency: in its 2016 and 2018 hybrid tables the code counts a failure when the frequency stays below 8 Hz with the fan enabled at 11 to 89 % duty for more than 8 s and system voltage above 10.2 V; 16 failures in 20 samples at 250 ms set it as Type B, two trips. A frequency near zero comes either from a fan that is not turning or from a feedback line shorted to ground or interrupted. The high case is P0BCA, a speed that is merely too far from the target is P0BC8, and drive circuit faults are P0A81 to P0A85. Expect power limits when the pack warms up.

Likely causes

Fan seized, blocked or without power
Feedback wire shorted to ground or interrupted
Failed speed sensor inside the fan unit

Symptoms

  • MIL on after two trips
  • No airflow from the battery cooling fan
  • Reduced power when the battery gets warm

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–500
Time0.5–2.5 h

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

Parts involved

battery cooling fanwiring harnessbms

Related codes

P0BCAP0BC8P0BC7P0BCBP0A84P0D61

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