P0B65: Hybrid/EV Battery Voltage Sense I Circuit Low

The 2012 GM two-mode hybrids show a detail worth knowing for P0B65: their battery pack control module only declares channel I, nickel-metal hydride block 9, too low when block 9 and its neighbour block 10 both read under 2 V, and only after 15 of 20 samples at 100 ms; the fault is Type B and needs two trips. A single weak block alone therefore does not set it. GM's lithium-ion controllers judge each cell on its own, setting P0B65 at 0.2 V or less held for 1.4 s within 2 s, Type A, as long as no open-line or communication fault has priority. The BAS Plus mild hybrid uses 1.4 V and 7 of 10 samples. In all cases the reading is too low to be a real cell.

Symptoms

• Hybrid system warning and MIL
• Engine runs more often, electric assist reduced
• Limited power in limp mode

Most likely causes

• Channel I sense lead shorted to ground or a lower tap
• Connector fault affecting adjacent blocks 9 and 10 (two-mode)
• Failed measuring input in the battery controller

What to check, in order

Start with the simplest. You can tick off each step.

1. Read the codes with a hybrid-compatible scanner and write down the freeze frame data
2. With the connector unplugged, check whether the signal wire is making contact with ground.
3. Make sure the battery cooling air intake is clean
4. Check the 12 V auxiliary battery, which can also trigger warnings
5. Leave any high-voltage measurements to a specialized repair shop

Good to know

• It can trigger limp mode.
• It affects emissions.

What each character of P0B65 means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• B: Subsystem depends on the code range
• 65: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0B65?

If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

What causes code P0B65?

The most common causes are: channel I sense lead shorted to ground or a lower tap; connector fault affecting adjacent blocks 9 and 10 (two-mode); failed measuring input in the battery controller.

Related codes

• P0B63Hybrid/EV Battery Voltage Sense I Circuit
• P0B64Hybrid/EV Battery Voltage Sense I Circuit Range/Performance
• P0B66Hybrid/EV Battery Voltage Sense I Circuit High
• P0B67Hybrid/EV Battery Voltage Sense I Circuit Intermittent/Erratic
• P0B60Hybrid/EV Battery Voltage Sense H Circuit Low
• P0B6AHybrid/EV Battery Voltage Sense J Circuit Low

Sources

• gsi.ext.gm.com: 12OBDG06 Hybrid Diagnostics
• gsi.ext.gm.com: 19OBDG01 Hybrid Diagnostics
• gsi.ext.gm.com: 13OBDG05C Hybrid Diagnostics
• law.cornell.edu: 13 CCR 1968.2

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.