P0B8F: Hybrid/EV Battery Voltage Sense Q Circuit Intermittent/Erratic

P0B8F closes the channel Q group and stands for a sense Q signal that is erratic rather than absent or out of range. No manufacturer documents this code publicly. GM's tables for sense Q, from the 2011 Volt to the 2019 battery controllers, list circuit, range, low and high monitors only, and the Ford Fusion bulletin ends four channels earlier at N. CARB 1968.2 forms the basis: it calls for monitoring of the battery voltage sensors in a hybrid energy storage system and for codes that lead a technician to the faulty part. Physically, an erratic Q reading would point to an unstable connection between tap and measuring chip, such as a cracked crimp, a damaged flexible circuit or a cold solder joint. The next channel, R, starts at P0B90.

Symptoms

• Sporadic hybrid or EV warning
• Power briefly reduced, normal after restart

Most likely causes

• Cracked crimp at the channel Q tap
• Damaged flexible circuit between cells and monitoring board
• Cold solder joint at the measuring chip

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. Gently move the wiring with the engine running and watch whether the reading changes.
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 P0B8F means

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

Frequently asked questions

Can I keep driving with code P0B8F?

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 P0B8F?

The most common causes are: cracked crimp at the channel Q tap; damaged flexible circuit between cells and monitoring board; cold solder joint at the measuring chip.

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
• P0B8EHybrid/EV Battery Voltage Sense Q Circuit High
• P0B8AHybrid/EV Battery Voltage Sense P Circuit Intermittent/Erratic
• P0B94Hybrid/EV Battery Voltage Sense R Circuit Intermittent/Erratic

Sources

• law.cornell.edu: 13 CCR 1968.2
• gsi.ext.gm.com: 19OBDG01 Hybrid Diagnostics
• gsi.ext.gm.com: 11OBDG01 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.