P0B98

What it means

P0B98 is the generic code for a high signal on the hybrid/EV battery voltage sense 'S' circuit. The battery control module saw a voltage on that sensing circuit above the expected range, or a signal that implies an open or shorted circuit. Which part of the pack or which sensor 'S' refers to depends on the model and manufacturer, so check the vehicle-specific service information.

Symptoms

• Hybrid system or check engine warning light on
• Reduced power or limp-mode behaviour
• Hybrid or EV battery not charging or discharging normally
• Car fails to enter Ready mode or switches to petrol-only running
• Battery charge gauge reading erratically or incorrectly

Possible causes

• Damaged, corroded or loose connector or wiring on the battery voltage sense circuitlikely
• Faulty battery voltage sensor or sensing circuit in the battery monitoring unitlikely
• Open or short in the sense circuit wiring, such as a short to a voltage supplypossible
• Fault in the battery control module itselfpossible
• Real battery cell or module imbalance or over-voltage conditionpossible
• Moisture or contamination in the battery pack or its connectorsrare
• Low-voltage (12 V) supply or earth problem upsetting the module's readingsrare

How to diagnose

1. Read all stored and pending codes and record the freeze frame data, noting battery voltage, temperature, state of charge and vehicle state when the code set.
2. Look for related codes, especially other battery voltage, sensor, or 12 V supply codes, and deal with those first if present.
3. Check the 12 V battery condition and charging, as a weak supply can cause false readings in the control modules.
4. Look up in the service information what the 'S' sense circuit is on this model and where its wiring and connectors run.
5. Using live data, compare the reported voltage with the other sense circuits and the total pack voltage to see whether the high reading is plausible.
6. Only if trained and qualified for high-voltage work, and after following the manufacturer's isolation procedure, inspect the sense wiring and connectors for damage, corrosion, moisture or looseness.
7. Test the sense circuit wiring for continuity and shorts to supply or earth, as the service information specifies.
8. If the wiring is sound, carry out the manufacturer's battery pack and monitoring unit tests to decide whether the sensor, module or the pack itself is at fault.

How to fix

• Repair or replace damaged wiring and clean or replace faulty connectors on the sense circuit.
• Replace the faulty voltage sensor or battery monitoring unit once testing confirms it.
• Replace or reprogram the battery control module if it is confirmed faulty, following the manufacturer's procedure.
• Rebalance, repair or replace the affected battery module or pack where a genuine voltage fault is found.
• Dry out and repair any moisture ingress, and fix the source of the leak.
• Apply a software update only if the manufacturer lists an outdated calibration as a known cause for this code.

Can I keep driving?

Nearby codes

• P0B97GenericHybrid/EV Battery Voltage Sense S Circuit Low
• P0B99GenericHybrid/EV Battery Voltage Sense S Circuit Intermittent/Erratic