What it means
The signals of the HV battery temperature sensors F and G do not correlate within the calibrated tolerance.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
HV battery temperature sensors F and G monitor temperatures at two cell-group locations, and the battery management system compares their readings for consistency. P0C86 sets when the F and G readings differ beyond the allowed correlation, which can result from either sensor being faulty or a problem in either sensor circuit.
Common causes
Most likely first.
- Faulty battery temperature sensor F or G
- Damaged wiring or poor connection in a sensor circuit
Symptoms
- EV/hybrid system warning light on
- Reduced power output or limp mode
- Charging may fail or be slowed
- Reduced electric range
How to diagnose it
- Use a hybrid-capable scan tool to save freeze-frame data and compare sensors F and G with each other and with nearby battery temperatures.
- Check whether the F-to-G difference changes plausibly with vehicle operation or remains skewed, fixed, or erratic.
- With the high-voltage system made safe per the manufacturer's procedure, inspect both sensor F and sensor G connectors and wiring for damage, corrosion, or loose contacts.
- Test the F and G sensor circuits and compare each sensor's response with the manufacturer's specifications to identify which reading is inaccurate.
- If both sensor circuits and readings pass, investigate the battery-pack temperature distribution and cell-group condition using the applicable manufacturer diagnostic procedure.
Common fixes
- Repair a loose, corroded, or damaged connection in the sensor F or G circuit.
- Repair damaged wiring affecting sensor F or sensor G.
- Replace whichever of sensors F or G fails the specified temperature-response test.
- Address any confirmed battery-pack condition causing an abnormal temperature difference.
Can I keep driving?
Avoid charging or hard driving if the hybrid warning or reduced-power mode is active, because the battery controller may limit operation when sensors F and G disagree. Stop if a battery-temperature warning appears or power drops substantially.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.