P0B93

What it means

P0B93 means the hybrid or EV battery control unit has seen the signal from one of the high-voltage battery voltage sense circuits (the one designated 'R') read higher than the expected range. It points to a fault in the sensing circuit or the sensing electronics, not necessarily a real over-voltage. Which cells, module or pack section the 'R' circuit monitors depends on the model, so check the manufacturer's data for that vehicle.

Symptoms

• Hybrid or EV system warning light on, often with the main warning lamp
• Reduced power or limp-home mode
• Hybrid battery charge and assist reduced or disabled
• Inaccurate or fluctuating battery charge level display
• Engine running more than normal on a hybrid, with poor economy
• Car refuses to enter Ready mode or shuts down the high-voltage system

Possible causes

• Damaged, corroded or loose wiring or connector on the battery voltage sense circuit, such as a short to a higher voltage or an open referencelikely
• Faulty battery monitoring unit or cell sensing board reporting a false high voltagelikely
• Faulty voltage sensor or sense harness inside the battery packpossible
• Genuine cell or module imbalance or over-voltage in the battery packpossible
• Poor connections at the pack, such as loose busbars or contaminated terminals, causing a false readingpossible
• Fault in the battery control unit, or an outdated calibration where the manufacturer has issued a fixrare

How to diagnose

1. Read all stored and pending codes plus freeze frame data. Note the battery voltage, temperature, state of charge and whether the fault is current or intermittent.
2. Check for related codes on other voltage sense circuits, cell balance or insulation. They can show whether the fault is isolated or pack-wide.
3. Look up the manufacturer's information for this model to find which part of the pack the 'R' circuit monitors and the expected voltage ranges.
4. Visually inspect accessible low-voltage wiring and connectors to the battery control unit for damage, water ingress, corrosion and pin tension. Only trained high-voltage technicians should isolate and open high-voltage components.
5. Watch live data for the battery block and cell voltages, and compare the 'R' reading with the others and with the total pack voltage. Look for a block that reads unrealistically high or jumps about.
6. With the high-voltage system isolated using the manufacturer's procedure, test the sense circuit wiring for continuity, shorts and resistance to specification.
7. Wiggle-test the harness with live data running to find intermittent faults.
8. Check for service bulletins or software updates for this model that relate to this code.

How to fix

• Repair or replace damaged wiring, terminals or connectors on the sense circuit.
• Clean and secure loose or contaminated connections, including pack busbars, to the manufacturer's procedure.
• Replace the faulty sensing board, monitoring unit or sensor if testing proves it is at fault.
• Rebalance or replace the affected battery module or pack if the over-voltage or imbalance is real.
• Apply a manufacturer calibration update only where an outdated calibration is a documented cause.
• Clear the code after the repair and road test to confirm it does not return.

Can I keep driving?

Nearby codes

• P0B92GenericHybrid/EV Battery Voltage Sense R Circuit Low
• P0B94GenericHybrid/EV Battery Voltage Sense R Circuit Intermittent/Erratic