What it means
The BMS detects a circuit low fault on voltage sense channel S of the high-voltage battery. Cell-group voltage measurement is unreliable on this channel.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The BMS uses channel S to measure the voltage of a high-voltage battery cell group. P0B97 sets when the channel S signal is lower than expected, so the BMS cannot rely on that group’s voltage reading.
Common causes
Most likely first.
- Sense wire shorted to ground
- Open in sense wire
- Connector pins corroded - high contact resistance
Symptoms
- EV/hybrid system warning light on
- Reduced power output or limp mode
- Charging may fail or be slowed
- Reduced electric range
How to diagnose it
- Save freeze-frame data and compare channel S with other battery voltage readings to see whether the signal is persistently low or the fault occurred under a specific condition.
- With the vehicle powered down as the manufacturer specifies, inspect channel S’s accessible wiring for damage or a short to ground.
- Have a qualified hybrid technician inspect channel S connector pins for corrosion or poor contact that could pull the signal low.
- Test the channel S sense wire for an open or short to ground using the manufacturer's procedure and specification.
- If the wiring and connector pass, compare the BMS channel S input with cell-group readings using the manufacturer's diagnostic procedure.
Common fixes
- Clean or repair corroded channel S connector pins.
- Repair channel S wiring that is open or shorted to ground.
- Replace a damaged connector or terminal causing high contact resistance.
- Repair or replace the battery monitoring component if testing confirms it is faulty.
Can I keep driving?
Avoid relying on electric power or charging while the BMS cannot trust channel S; the vehicle may limit power or enter limp mode. Arrange prompt diagnosis and stop safely if power becomes inadequate for traffic.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.