What it means
The BMS detects a circuit high 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 measures a high-voltage battery cell group through voltage sense channel S. P0B98 sets when the channel S signal rises above the expected range, making the cell-group voltage reading unreliable.
Common causes
Most likely first.
- Sense wire shorted to higher voltage
- Reference regulator overvoltage
- 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 the other battery voltage readings to check whether the high signal is constant or condition-dependent.
- With the vehicle powered down as the manufacturer specifies, inspect channel S wiring and connectors for damage, corrosion, or contact with a higher-voltage point.
- Have a qualified hybrid technician check channel S connector seating and terminal condition for poor contact.
- Test channel S for a short to a higher-voltage circuit and check its reference supply according to the manufacturer's procedure and specification.
- If wiring and reference supply checks pass, use the manufacturer's diagnostic procedure to assess the BMS input and reference regulator.
Common fixes
- Repair channel S wiring shorted to a higher-voltage circuit.
- Clean or replace corroded or damaged channel S connector terminals.
- Repair a faulty reference supply or regulator if testing confirms overvoltage.
- Repair or replace the BMS component if tests isolate the fault there.
Can I keep driving?
Limit driving and avoid charging until the high channel S signal is diagnosed; the BMS may reduce power or restrict charging. Stop safely if limp mode or a significant power drop occurs.
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.