P0B89: Hybrid/EV Battery Voltage Sense P Circuit High

P0B89 covers the opposite case to P0B88: the voltage reported on channel P is above the plausible range. GM's 2012 two-mode hybrids assign P to NiMH block 16 and set the code when the block exceeds 23 V in 15 of 20 samples at 100 ms, Type B, provided no battery controller fault P0A1F is active. In lithium-ion systems GM sets 4.8 V or more for 1.4 s in 2 s as the limit, Type A, while the BAS Plus mild hybrid reacts above 4.65 V. GM's 2016 program with a separate sense module allows up to 4.90 V. Overcharging is unlikely to be the cause because the controller stops charging well below these values; a sense lead reaching a higher tap or an input fault is the usual explanation. Expect restricted charging.

High severity. Can I keep driving?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.

Symptoms

Charging restricted
MIL and hybrid warning

Most likely causes

Lead P in contact with a higher cell tap
Input fault in the cell monitoring electronics
Genuine overvoltage of the cell or block

What to check, in order

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

Read the codes with a hybrid-compatible scanner and write down the freeze frame data
Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
Make sure the battery cooling air intake is clean
Check the 12 V auxiliary battery, which can also trigger warnings
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 P0B89 means

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

Frequently asked questions

Can I keep driving with code P0B89?

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 P0B89?

The most common causes are: lead P in contact with a higher cell tap; input fault in the cell monitoring electronics; genuine overvoltage of the cell or block.

Related codes

Sources

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.