Powertrain, generic · Hybrid propulsion

P0C9A Hybrid/EV Battery Temperature Sensor L Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P0C9A is the high-voltage fault of sensor L: an open thermistor, a broken lead or a disconnected plug lets the bias resistor raise the input, and the reading looks like deep frost. GM's 2016 table 16OBDG02 sets it when 8 readings out of 10, taken every 100 ms, are colder than −69 °C; it is Type B and requires more than 10.2 V supply plus working communication. The 2012 Volt table treats readings below −40 °C, a raw count above 4,000, as failed. Mitsubishi assigns no code to sensor L. The controller then plans for a frozen battery, so electric power can be reduced and a plug-in may run its battery heater or engine. Check the plug at the monitoring board first; P0C99 is the short-circuit partner.

Likely causes

Open circuit or unplugged connector at sensor L
Thermistor L open internally
Corroded terminal with very high contact resistance

Symptoms

  • Battery-too-cold indication in mild conditions
  • Electric power reduced, engine running more on plug-ins

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–2,500
Time0.5–5 h

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

Parts involved

hv battery temp sensor lwiring harnessbms

Related codes

P0C99P0C98P0C97P0C9BP0C95P0CAB

References: gsi.ext.gm.com, gsi.ext.gm.com.