P0B58

What it means

P0B58 is a generic powertrain code meaning the hybrid or EV battery control unit has seen an intermittent or erratic signal from the 'F' battery voltage sense circuit. The reading jumps, drops out or does not agree with the other voltage sensing, so the control unit cannot trust it. Which cell block or sensing point 'F' refers to depends on the vehicle and battery design, so check the manufacturer data for the model.

Symptoms

• Hybrid or EV system warning light, or malfunction indicator lamp, on
• Reduced power or the car going into a limited performance mode
• Reduced or fluctuating electric-assist or regenerative braking
• State of charge reading that jumps or looks wrong
• Hybrid battery not charging or discharging as normal
• Fault that comes and goes, often with vibration or temperature change

Possible causes

• Loose, corroded or damaged connector on the battery voltage sensing circuitlikely
• Damaged, chafed or broken wiring in the voltage sense harnesslikely
• Poor contact at a sense terminal or busbar connection on the battery packpossible
• Faulty battery monitoring module or cell sensing circuit inside the packpossible
• Moisture or contamination in the battery pack or its connectorspossible
• Fault in the hybrid battery control unit or an outdated software calibration, where the manufacturer lists it as a known causerare

How to diagnose

1. Read all stored and pending codes plus freeze frame data, noting battery state, temperature, vehicle speed and whether other battery voltage or sensor codes are present
2. Look up the manufacturer data to identify which sensing circuit 'F' refers to on this model and where its connectors and harness run
3. Before touching any high-voltage parts, follow the manufacturer's high-voltage safety procedure, and only let suitably trained and equipped staff work on the battery system
4. Inspect the visible harness and connectors for chafing, corrosion, water ingress, bent pins or loose fit, and gently wiggle the harness with live data on display to see if the voltage reading jumps
5. Watch the live voltage sense data and compare it with the other cell or block voltages for sudden spikes, drop-outs or readings that disagree
6. Check the low-voltage supply and earth connections to the battery control unit, as poor supply can cause erratic readings
7. Inspect the battery pack seals, cooling air ducts and surrounding area for moisture, debris or damage, following the manufacturer's procedure
8. Check for technical service bulletins or software updates for this model that cover the fault

How to fix

• Clean, refit or replace damaged or corroded connectors and terminals on the sense circuit
• Repair or replace the damaged section of wiring in line with the manufacturer's repair procedure
• Rectify poor contact at the sense terminals or busbar connections on the pack, using a trained high-voltage technician
• Replace the faulty battery monitoring module or sensing component if testing confirms it has failed
• Update the control unit software only if the manufacturer lists an outdated calibration as a known cause for this fault

Can I keep driving?

Nearby codes

• P0B57GenericHybrid/EV Battery Voltage Sense F Circuit High
• P0B59GenericHybrid/EV Battery Voltage Sense G Circuit