Faulty battery temperature sensor F or G giving a drifting or incorrect reading; Damaged wiring, poor connection or corroded terminals in the sensor circuit; Restricted airflow or a failing cooling fan or coolant circulation causing a genuine temperature difference across the pack; Blocked battery cooling intake duct or dirty filter (on air-cooled packs); Fault in the battery monitoring module or control unit; Internal battery pack fault causing a real hot spot in one area.

P0C86

Hybrid/EV Battery Temperature Sensor F/G Correlation.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
C: AreaHybrid propulsion
86: FaultThe specific fault in that area

What it means

P0C86 is a generic powertrain code meaning the hybrid or EV battery temperature sensor F and sensor G readings do not correlate with each other. The battery control unit compares the two sensors, which are expected to read similarly under the same conditions, and saw a difference larger than allowed. The exact positions of sensors F and G depend on the make, model and battery design.

Symptoms

Hybrid or EV system warning light on
Reduced power or limited electric assist
Reduced charging rate or charging stopping early
Battery cooling fan running louder or more often than normal
Reduced electric-only range or the engine running more often on a hybrid

Possible causes

Faulty battery temperature sensor F or G giving a drifting or incorrect readinglikely
Damaged wiring, poor connection or corroded terminals in the sensor circuitlikely
Restricted airflow or a failing cooling fan or coolant circulation causing a genuine temperature difference across the packpossible
Blocked battery cooling intake duct or dirty filter (on air-cooled packs)possible
Fault in the battery monitoring module or control unitrare
Internal battery pack fault causing a real hot spot in one arearare

How to diagnose

Read all stored and pending codes and note any other battery temperature, cooling fan or battery module codes
Review freeze frame data to see pack temperatures, ambient temperature and vehicle state when the code set
Compare live data for all battery temperature sensors on a cool pack after the car has been left to stand, as they should read close to each other and to ambient
Inspect the battery cooling intake, ducting and filter for blockage, debris or damage, following the manufacturer's high-voltage safety procedure
Check that the cooling fan or coolant circuit operates correctly when commanded with a scan tool
Inspect the sensor wiring and connectors for damage, moisture and corrosion, only after the high-voltage system is isolated by a suitably trained person
Test the sensor resistance and circuit continuity against the manufacturer's specification, which varies by model
Check for software updates or technical bulletins for the specific model before replacing the battery control unit

How to fix

Replace the faulty temperature sensor or sensor harness section as the manufacturer specifies
Repair or replace damaged wiring, connectors or terminals
Clear the blocked cooling duct or replace the dirty filter
Repair or replace the battery cooling fan or fix the coolant circulation fault
Update or replace the battery control module only if testing confirms it is faulty or a known software issue applies
Have the battery pack inspected by a qualified high-voltage technician if a real hot spot is confirmed

Can I keep driving?

Medium severity

The car can usually be driven short distances, but expect reduced performance and fix it soon, as poor battery temperature monitoring can lead to pack damage. Stop driving and seek help if you see a battery overheating warning, smell burning or notice unusual heat.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.