P0C84 code meaning
Hybrid/EV Battery Temperature Sensor H Circuit High
Powertrain system Generic code P0Cxx codes Check engine light
What P0C84 means
P0C84 is set when the sensor H line sits too high in voltage, which the controller converts into an impossible cold reading. The pull-up drives an interrupted circuit upward, so an open wire, a pushed-out pin or a broken thermistor are the classic triggers. In GM's 2012 Volt table (12OBDG01A) the limit is below −40 °C, an ADC count above 4000, held for 1.4 s within a 2 s window; the 2019 table 19OBDG02 uses −69 °C in 8 of 10 samples, Type B. Mitsubishi's Outlander PHEV of 2022 sees an open of sensor [07] above 3.97 V, below −62 °C, for 2 s. A cold-weather complaint with a Battery Too Cold message on the Volt may be software, per bulletin 18-NA-342. The short-to-ground counterpart is P0C83.
P0C84 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor0.5 to 5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0C84
- Battery-too-cold message in mild weather
- Electric drive limited or unavailable
Common causes of P0C84
- Most likelyBroken wire or backed-out pin in the sensor H circuit
- PossibleThermistor H open
- Less likelyFalse set by battery module software (GM Volt, 18-NA-342)
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 P0C84 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. |
| 84 | The exact fault in that area. |
What to do next
- Note P0C84 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 P0C84
What does P0C84 mean?
P0C84 means "Hybrid/EV Battery Temperature Sensor H Circuit High". P0C84 is set when the sensor H line sits too high in voltage, which the controller converts into an impossible cold reading. It is a generic code, so it means the same on every make.
Is it safe to drive with P0C84?
Drive gently and only to a workshop. With P0C84 the car can go into limp mode (reduced power) to protect itself.
Will P0C84 fail an emissions test?
Yes, it can. P0C84 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 P0C84 to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 5 hours of work. This is a job for a workshop.
Will P0C84 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.