P0B4D: Hybrid/EV Battery Voltage Sense D Circuit High

P0B4D sets when cell sense channel D reports more voltage than the cell or block behind it can deliver. GM's limits are 4.8 V or more for 1.4 s within 2 s on lithium-ion packs (battery energy control module, Type A, one trip) and above 23 V for block 4 of the 2012 two-mode hybrids (15 of 20 samples, Type B, two trips). A practical first check is live data: if channel D sits far above its neighbours while the pack voltage and the other channels look normal, the fault is in the sense path, not in the cells. Typical findings are a sense lead that contacts a higher tap or a damaged measuring input. The controller limits power until the code is repaired.

Symptoms

• MIL and battery system warning
• Reduced acceleration and regenerative braking
• Charging power limited or charging refused

Most likely causes

• Channel D sense lead contacting a tap of higher potential
• Damaged measuring input in the monitoring electronics
• Moisture or contamination on the monitoring board creating leakage paths

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 P0B4D means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• B: Subsystem depends on the code range
• 4D: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0B4D?

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 P0B4D?

The most common causes are: channel D sense lead contacting a tap of higher potential; damaged measuring input in the monitoring electronics; moisture or contamination on the monitoring board creating leakage paths.

Related codes

• P0B4AHybrid/EV Battery Voltage Sense D Circuit
• P0B4BHybrid/EV Battery Voltage Sense D Circuit Range/Performance
• P0B4CHybrid/EV Battery Voltage Sense D Circuit Low
• P0B4EHybrid/EV Battery Voltage Sense D Circuit Intermittent/Erratic
• P0B48Hybrid/EV Battery Voltage Sense C Circuit High
• P0B52Hybrid/EV Battery Voltage Sense E Circuit High

Sources

• gsi.ext.gm.com: 19OBDG01 Hybrid Diagnostics
• gsi.ext.gm.com: 12OBDG06 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.