P0CA8 is the general circuit code for battery temperature sensor M, meant for electrical faults that the controller does not sort into low, high or erratic. No manufacturer publishes this exact code. In GM's 2011 Volt table the rationality list gives M the thirteenth of sixteen positions, yet GM only defines P0CA9 to P0CAC for it. Mitsubishi's Outlander PHEV assigns M to module sensor [12] and also uses only the rationality, short and open codes. CARB section (e)(15.3.1) requires continuous checks of range and continuity for inputs of this kind. Without a usable value the battery controller must assume a hot module section and restricts power. Repair means opening the made-safe traction battery and checking the sensor, its leads and the plug at the monitoring board.
High severity. Can I keep driving?If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.
Symptoms
- Hybrid or EV warning, possibly with check-engine lamp
- Electric power reduced until repaired
Most likely causes
- Poor contact at the plug of sensor M on the monitoring board
- Thermistor M damaged
- Faulty input channel of the cell monitoring board
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- It can trigger limp mode.
- It affects emissions.
What each character of P0CA8 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- C: Subsystem depends on the code range
- A8: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0CA8?
If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.
What causes code P0CA8?
The most common causes are: poor contact at the plug of sensor M on the monitoring board; thermistor M damaged; faulty input channel of the cell monitoring board.
Related codes
- P0CA9Hybrid/EV Battery Temperature Sensor M Circuit Range/Performance
- P0CAAHybrid/EV Battery Temperature Sensor M Circuit Low
- P0CABHybrid/EV Battery Temperature Sensor M Circuit High
- P0CACHybrid/EV Battery Temperature Sensor M Circuit Intermittent/Erratic
- P0C97Hybrid/EV Battery Temperature Sensor L Circuit
- P0CADHybrid/EV Battery Temperature Sensor N Circuit
Sources
- law.cornell.edu: 13 CCR 1968.2
- gsi.ext.gm.com: 11OBDG01 HYBRID Diagnostics
- mitsubishitechinfo.com: M154940060025701USA
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.