P2C87Hybrid/EV Battery Voltage External Isolation Warning
- Generic OBD-II code · Powertrain
- Can trigger limp mode
- How the car detects it
- P2C87 is the warning stage for weakening insulation outside the battery, on the vehicle-side high-voltage network. Many systems use two limits; Volkswagen's ID.4, for example, shows a yellow lamp below 510 kOhm and a red one below 90 kOhm. Mercedes-Benz stores P2C8700 for an insulation warning on the vehicle side, listed in its 2024 extended warranty for plug-in hybrids with a corroding high-voltage A/C compressor and in a 2025 bulletin on a moist PTC heater. Volvo logs P2C871A in the BECM of the EX30: if it appears together with P128300 in VCU1 and the car will not engage a gear or reports reduced power, Technical Journal 37771 has the combined charger and DC/DC module replaced. If the fault grows, P2C85 follows.
- What you may notice
- Yellow high-voltage or battery warning
- Reduced power or no gear engagement on some models
- Intermittent, often after rain or washing
- Likely causes
- LikelyMoisture or corrosion in an external HV component (compressor, heater, charger)
- PossibleInsulation fault inside the on-board charger or DC/DC converter
- PossibleDirty or wet high-voltage connector
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €200 – €4,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.