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Powertrain Source reviewed Lights the check engine lamp

P0BB6: Hybrid/EV Battery Voltage Sense Y Circuit High

Standardized SAE J2012 code · P0Bxx — Hybrid and electric propulsion

Safety-critical system. Faults in airbags, brakes, steering or high-voltage components can put people at risk. Follow the manufacturer's service information and safety procedures, or have the vehicle checked by a qualified workshop.

What does P0BB6 mean?

The battery controller logs P0BB6 when the Y channel climbs above a level no healthy cell reaches. GM's first Volt of 2011 put that limit at 4.8 V or more, 1.4 s within 2 s, with the MIL after one trip. The 16OBDG02 programme samples every 100 ms and fails above 4.90 V in 14 of 18 samples, Type A; the eAssist battery fails above 4.65 V in seven of ten samples at 200 ms, Type B. A wiring fault that connects the Y input to the potential of the next cell is the most common explanation, followed by a failed input. Overcharging of a single cell is possible after a balancing problem and must be ruled out before the pack is charged again.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

  • MIL and charging stopped
  • Regeneration disabled

Common causes

  • High Sense input Y bridged to the next cell potential
  • Medium Defective input Y on the monitoring board
  • Low Overcharged cell Y after a balancing problem

Likelihood is a general estimate across vehicles; your make and model may differ.

Add your car to see reports of P0BB6 on the same make and model first.

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