P0D85: Battery Charging Output Voltage Too High

What it means

The battery charging output voltage exceeds the safe upper limit. Risk of cell damage from overvoltage during charging.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

The battery charger regulates the voltage delivered to the traction battery and monitors feedback to keep charging within safe limits. P0D85 sets when the reported charging output voltage exceeds the permitted upper range, potentially because charger regulation is off target or voltage feedback is lost.

Common causes

Most likely first.

1. Charger regulation off-target
2. Voltage feedback lost

Symptoms

• Charging-system warning light or message
• Charging may stop or be limited

How to diagnose it

1. Review freeze-frame and charging data for the reported output voltage and whether charging stopped or was limited when the fault appeared.
2. Check for other battery, charger, or voltage-sensing codes that could help identify whether regulation or feedback is involved.
3. Stop charging and inspect accessible charging connectors for damage or overheating without opening high-voltage components.
4. Have a qualified technician verify charging output and battery voltage feedback against the manufacturer's specification using the prescribed high-voltage safety procedure.
5. If the feedback circuit is intact, test the onboard charger's regulation and control components for an overvoltage fault.

Common fixes

• Repair a damaged voltage-feedback connection or wiring fault confirmed by testing.
• Replace a faulty voltage-sensing component if it is shown to be misreporting output.
• Repair or replace the onboard charger if its regulation is confirmed to be producing excessive voltage.

Can I keep driving?

Charging may stop or be restricted to protect the battery, and continued overvoltage can damage battery cells. Do not keep attempting to charge with this fault active; have the high-voltage charging system checked promptly.