What are the common causes of P0DC9?

Balancing circuit H contactor held closed. A short on the circuit H control line. A balance resistor in circuit H failed short. Moisture in the circuit H connector. A monitoring module fault holding circuit H on.

Watch cell voltages for a slow drain with the key off. Test the circuit H switch for a stuck closed contact. Check circuit H for a short to power. Dry and reseat the circuit H connector. Replace the battery monitoring module if circuit H will not release. Clear the code and retest.

P0DC9

Hybrid/EV Battery Cell Balancing Circuit H Stuck On

System: Powertrain control (P code)
Lamp: Check Engine Light
Category: Powertrain - Hybrid Propulsion

What it means

P0DC9 means Hybrid/EV Battery Cell Balancing Circuit H Stuck On.

Check these first

Balancing circuit H contactor held closed
A short on the circuit H control line
A balance resistor in circuit H failed short
Moisture in the circuit H connector
A monitoring module fault holding circuit H on

What to do next

Watch cell voltages for a slow drain with the key off
Test the circuit H switch for a stuck closed contact
Check circuit H for a short to power
Dry and reseat the circuit H connector
Replace the battery monitoring module if circuit H will not release
Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.