P0C85 code meaning
Hybrid/EV Battery Temperature Sensor H Circuit Intermittent/Erratic
Powertrain system Generic code P0Cxx codes Check engine light
What P0C85 means
P0C85 points to a sensor H reading that flickers. A battery pack warms and cools slowly, so fast swings in one channel suggest an electrical contact problem rather than real heat. GM's 2018 hybrid table 18OBDG02 adds up how much the value moves within a 10-sample window at 100 ms per sample; once that sum passes 10 in 4 of 5 evaluations, the module logs P0C85, Type B over two trips, as long as the supply exceeds 10.2 V and the battery interface module is talking. The 2019 table 19OBDG02 keeps the same rule. GM's OBDG01 tables of 2011 to 2016 (first-generation Volt, ELR) and Mitsubishi list no such code for sensor H. A wiggle test on the harness while watching live data usually finds the fault; low or high voltage faults are P0C83 and P0C84 instead.
P0C85 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0C85
- Intermittent warning lamp
- Sensor H value jumping in live data
Common causes of P0C85
- Most likelyIntermittent contact at the sensor H terminal
- PossiblePartly broken sensor H wire inside the pack harness
- Less likelyNoisy measuring channel on the sensing board
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv battery temp sensor hWiring harnessBms
What each part of P0C85 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| C | Area: hybrid propulsion. |
| 85 | The exact fault in that area. |
What to do next
- Note P0C85 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0C85
What does P0C85 mean?
P0C85 means "Hybrid/EV Battery Temperature Sensor H Circuit Intermittent/Erratic". P0C85 points to a sensor H reading that flickers. It is a generic code, so it means the same on every make.
Is it safe to drive with P0C85?
Drive gently and only to a workshop. With P0C85 the car can go into limp mode (reduced power) to protect itself.
Will P0C85 fail an emissions test?
Yes, it can. P0C85 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0C85 to fix?
Difficulty: workshop only. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will P0C85 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.