P0B49: Hybrid/EV Battery Voltage Sense C Circuit Intermittent/Erratic

P0B49 is reserved for a channel C signal that jumps or drops out briefly instead of failing for good. No manufacturer documents this code publicly; GM, which uses the other four channel C codes, has no erratic test for it in its published tables. A technician would start from the freeze frame and log cell voltage C next to its neighbours while flexing the module harness, because a loose crimp or a cracked solder joint on the monitoring board shows up as spikes that a permanent test misses. CARB requires battery voltage sensors of the energy storage system to be monitored like any input and faults to be tied to the smallest replaceable unit. Warnings may come and go.

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

Warning light that appears and disappears
Occasional short loss of electric drive power

Most likely causes

Loose crimp or connector on the channel C sense line
Cracked solder joint on the cell monitoring board
Electrical noise from the inverter coupling into the sense line

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
Gently move the wiring with the engine running and watch whether the reading changes.
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 P0B49 means

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

Frequently asked questions

Can I keep driving with code P0B49?

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 P0B49?

The most common causes are: loose crimp or connector on the channel C sense line; cracked solder joint on the cell monitoring board; electrical noise from the inverter coupling into the sense line.

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.