P0B9D: Hybrid/EV Battery Voltage Sense T Circuit High

If sense T reports more voltage than its cell can hold, the battery controller stores P0B9D. GM documents it on several systems. The 2019 battery energy control module and the 2016 Volt set it at 4.8 V or above for 1.4 s within 2 s, Type A, and only when no open sense line fault is pending. The 16OBDG02 programme with a dedicated battery sensor module uses 4.90 V in 14 of 18 samples. The eAssist mild hybrid sets it above 4.65 V in 7 of 10 samples, Type B. In the 2012 two-mode trucks the channel is block 20, the final NiMH block, with a limit of 23 V and 15 of 20 samples, Type B. Most such readings come from wiring touching a higher potential or a faulty measuring input.

Symptoms

• MIL and service hybrid or EV system message
• Charging power reduced

Most likely causes

• Sense lead T shorted to a higher cell or busbar
• Measuring input for channel T drifting high
• Cell or block T genuinely overcharged

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 P0B9D means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• B: Subsystem depends on the code range
• 9D: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0B9D?

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 P0B9D?

The most common causes are: sense lead T shorted to a higher cell or busbar; measuring input for channel T drifting high; cell or block T genuinely overcharged.

Related codes

• P0B9AHybrid/EV Battery Voltage Sense T Circuit
• P0B9BHybrid/EV Battery Voltage Sense T Circuit Range/Performance
• P0B9CHybrid/EV Battery Voltage Sense T Circuit Low
• P0B9EHybrid/EV Battery Voltage Sense T Circuit Intermittent/Erratic
• P0B98Hybrid/EV Battery Voltage Sense S Circuit High
• P0BA2Hybrid/EV Battery Voltage Sense U Circuit High

Sources

• gsi.ext.gm.com: 19OBDG01 Hybrid Diagnostics
• gsi.ext.gm.com: 16OBDG02 Hybrid Diagnostics
• gsi.ext.gm.com: 13OBDG05C Hybrid Diagnostics
• gsi.ext.gm.com: 12OBDG06 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.