Powertrain, generic · Hybrid propulsion

P0CA8 Hybrid/EV Battery Temperature Sensor M Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

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.

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

Symptoms

  • Hybrid or EV warning, possibly with check-engine lamp
  • Electric power reduced until repaired

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€150–2,500
Time1–5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

hv battery temp sensor mwiring harnessbms

Related codes

P0CA9P0CAAP0CABP0CACP0C97P0CAD

References: law.cornell.edu, gsi.ext.gm.com, mitsubishitechinfo.com.