P0BA9Hybrid/EV Battery Voltage Sense W Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P0BA9 opens the W group, the twenty-third cell voltage channel, and flags a sense lead that is open or badly connected. GM's 2019 battery energy control module checks seven cases, ranging from a reading under 36 mV while the balancing gate of that cell is switched on to at least 1.3 V between neighbouring cells and splice voltages above 0.1 V or 0.5 V at busbar joints; 0.8 s of failure within 1.6 s sets it as Type A. The 2016 Volt module uses a 0.6 s window instead. GM's eAssist mild hybrid needs readings under 1.4 V on lines N and N-1 plus a change of more than 0.5 V within 200 ms in seven of ten samples, Type B. With the lead lost, the cell behind it can neither be balanced nor protected.
- What you may notice
- MIL with hybrid or EV system warning
- Reduced propulsion power or no ready mode
- Charging interrupted or refused
- Likely causes
- LikelyBroken, chafed or unplugged sense lead W
- PossibleHigh-resistance busbar or splice joint at channel W
- RareFailed input on the cell monitoring board for W
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €150 – €7,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.