P0C99Hybrid/EV Battery Temperature Sensor L Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P0C99 reports a sensor L voltage below the valid range. Because the thermistor works against a bias resistor on its monitoring board, any ground fault or an internally shorted sensor drags the voltage down, which reads as a very hot module. GM's 2019 HPC2 table 19OBDG02 flags it once the converted value exceeds 160 °C in 8 out of 10 readings at 100 ms intervals; it is a Type B code and needs supply above 10.2 V. The 2012 Volt table groups L with the other sensors and passes them only at or below 87.5 °C, which equals a raw count of 680 or more, and needs 1.4 s out of 2 s to fail. Mitsubishi does not use L codes. If the pack is really overheating, P0A7E appears instead. Expect a warning lamp and reduced battery power.
- What you may notice
- Warning lamp and reduced battery power
- Battery cooling running for no apparent reason
- Likely causes
- LikelySensor L signal shorted to ground
- PossibleThermistor L shorted internally
- RareMonitoring board channel pulling the input low
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €150 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.