P2C85
Low Severity (Level 2)Hybrid/EV Battery Voltage External Isolation Fault
P2C85 usually means hybrid/EV Battery Voltage External Isolation Fault.
Can you still drive with P2C85?
⚠️Short-distance driving is usually OK, but have this diagnosed within a week to prevent further damage.
Typical repair cost: $100 – $500
Severity Level 2 — Low
This code indicates a minor issue that is unlikely to cause immediate driveability problems. You can typically continue driving but should have the vehicle inspected at your earliest convenience.
Common Symptoms
- Warning light or malfunction indicator related to the battery voltage/system voltage is illuminated
- The battery voltage/system voltage is not operating as designed
- Diagnostic trouble code (DTC) stored in module memory
- Fault may be intermittent — code may clear itself and reappear
- Reduced vehicle functionality related to the battery voltage/system voltage
Possible Causes
- Faulty battery — most common cause, test before replacing
- Damaged or corroded wiring/connector in the battery voltage/system voltage circuit
- Blown fuse or faulty relay for the battery voltage/system voltage
- Poor ground connection — check and clean all related ground points
- Control module fault — rare but possible, only consider after ruling out simpler causes
Common Fixes
- Scan vehicle with a professional-grade OBD2 scanner to read all stored codes and freeze frame data — note the conditions when the code set ($36-84 at shop, free at auto parts store for basic scan)
- Visually inspect the battery voltage/system voltage wiring harness and connectors — look for chafed wires, melted insulation, green corrosion, loose pins, or rodent damage (often free to check yourself, $147 diagnostic fee at shop)
- Replace battery if testing confirms it has failed — use OEM quality, avoid the cheapest no-name aftermarket parts that fail in a year ($100-500)
- Check and replace any blown fuses in the battery voltage/system voltage fuse circuit — if fuse blows again, there's still a short that needs to be found ($5-13 for fuses)
- Perform a wiggle test on the battery voltage/system voltage wiring harness while monitoring live data — see if the fault returns when you move the harness at different points ($0-136 diagnostic labor)
Estimated Repair Cost
These are estimated costs based on generic repair data. Actual costs may vary depending on your vehicle, location, and labor rates.
Frequently Asked Questions
What does P2C85 mean?
P2C85 stands for "Hybrid/EV Battery Voltage External Isolation Fault". P2C85 usually means hybrid/EV Battery Voltage External Isolation Fault.
Can you drive with P2C85?
Short-distance driving is usually OK, but have this diagnosed within a week to prevent further damage.
How much does it cost to fix P2C85?
Repair costs for P2C85 typically range from $100 to $500, depending on your vehicle make, model, and local labor rates. Common fixes include: Scan vehicle with a professional-grade OBD2 scanner to read all stored codes and freeze frame data — note the conditions when the code set ($36-84 at shop, free at auto parts store for basic scan); Visually inspect the battery voltage/system voltage wiring harness and connectors — look for chafed wires, melted insulation, green corrosion, loose pins, or rodent damage (often free to check yourself, $147 diagnostic fee at shop); Replace battery if testing confirms it has failed — use OEM quality, avoid the cheapest no-name aftermarket parts that fail in a year ($100-500).
Will P2C85 clear itself?
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