P0B8E: Hybrid/EV Battery Voltage Sense Q Circuit High

Channel Q reporting an implausibly high voltage sets P0B8E. On the 2012 GM two-mode hybrids, where Q is NiMH block 17, the limit is 23 V for 15 of 20 samples, Type B, checked only while the 12 V system lies between 9 and 18 V. GM's lithium-ion programs work at cell level: 4.8 V or more for 1.4 s in 2 s in the 2016 and 2019 battery controllers, more than 4.90 V in 14 of 18 samples where a separate battery sense module measures, all Type A. The BAS Plus mild hybrid limit is 4.65 V. As with the other high codes of this family, wiring and measuring input are far more often to blame than the cell; a damaged harness that lets lead Q touch the next tap is a classic finding. Charging and regeneration are limited.

Symptoms

• Regeneration and charging limited
• MIL and battery system warning

Most likely causes

• Damaged harness letting lead Q touch the next tap
• Measuring input of channel Q reading high
• Real cell overvoltage after a balancing failure

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. Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
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 P0B8E means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• B: Subsystem depends on the code range
• 8E: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0B8E?

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 P0B8E?

The most common causes are: damaged harness letting lead Q touch the next tap; measuring input of channel Q reading high; real cell overvoltage after a balancing failure.

Related codes

• P0B8BHybrid/EV Battery Voltage Sense Q Circuit
• P0B8CHybrid/EV Battery Voltage Sense Q Circuit Range/Performance
• P0B8DHybrid/EV Battery Voltage Sense Q Circuit Low
• P0B8FHybrid/EV Battery Voltage Sense Q Circuit Intermittent/Erratic
• P0B89Hybrid/EV Battery Voltage Sense P Circuit High
• P0B93Hybrid/EV Battery Voltage Sense R Circuit High

Sources

• gsi.ext.gm.com: 12OBDG06 Hybrid Diagnostics
• gsi.ext.gm.com: 16OBDG01 Hybrid Diagnostics
• gsi.ext.gm.com: 16OBDG02 Hybrid Diagnostics
• gsi.ext.gm.com: 13OBDG05C Hybrid Diagnostics

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.