P0CB4 code meaning
Hybrid/EV Battery Temperature Sensor O Circuit Low
Powertrain system Generic code P0Cxx codes Check engine light
What P0CB4 means
P0CB4 reports a signal voltage of sensor O below its lower limit. The sensor is an NTC thermistor biased by a resistor on the measuring board, so a short to ground or a shorted element looks like extreme heat. GM's HPC2 table 18OBDG02 fails the test when the converted value is above 160 °C in 8 of 10 readings at 100 ms, Type B, with more than 10.2 V supply; the 2011 Volt table used 87.5 °C, a raw count below 680, for 1.4 s within a 2 s window over two trips. In GM's 2019 table the pack over-temperature monitor P0A7E is suspended while such short codes are active, because a false hot reading would otherwise trigger it. Mitsubishi calls P0CB4 a short of module sensor [14] on the Outlander PHEV: under 0.12 V, roughly above 125 °C, for 2 s.
P0CB4 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 P0CB4
- Live data showing an implausibly hot module
- Strongly reduced battery power with warning lamp
- Battery cooling running without obvious need
Common causes of P0CB4
- Most likelySignal lead of sensor O shorted to ground in the pack
- PossibleThermistor O shorted internally
- Less likelyInput stage of the cell monitoring unit defective
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 oWiring harnessBms
What each part of P0CB4 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. |
| B4 | The exact fault in that area. |
What to do next
- Note P0CB4 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 P0CB4
What does P0CB4 mean?
P0CB4 means "Hybrid/EV Battery Temperature Sensor O Circuit Low". P0CB4 reports a signal voltage of sensor O below its lower limit. It is a generic code, so it means the same on every make.
Is it safe to drive with P0CB4?
Drive gently and only to a workshop. With P0CB4 the car can go into limp mode (reduced power) to protect itself.
Will P0CB4 fail an emissions test?
Yes, it can. P0CB4 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 P0CB4 to fix?
Difficulty: workshop only. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will P0CB4 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.