What it means
The HV battery pack coolant heater B reports a control circuit low condition. Battery preheating may be impaired in cold weather.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Battery coolant heater B heats coolant to help the high-voltage battery reach a suitable temperature in cold conditions. The control module monitors heater B's control-circuit voltage and sets P0E17 when it is lower than expected, which can result from a short to ground or an abnormal load.
Common causes
Most likely first.
- Wire shorted to ground
- Element internal short
- Connector pins corroded - high contact resistance
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
- Read freeze-frame and hybrid-system live data to check the battery temperature, heater B command, and conditions when the low-circuit fault was recorded.
- With the vehicle powered down as specified by the manufacturer, inspect heater B's wiring and connector for chafing, moisture, corrosion, or damaged terminals that could pull the circuit low.
- Use the manufacturer's wiring diagram and procedure to test the heater B control wire for a short to ground.
- Check heater B's element and connector for an internal short or excessive load using the manufacturer's specified test.
- If the circuit and element are sound, verify the commanded output and control-module response using the manufacturer's diagnostic procedure.
Common fixes
- Repair heater B wiring that is shorted to ground.
- Clean or replace corroded heater B connector terminals.
- Repair damaged insulation or a loose connection at heater B.
- Replace heater B if its element tests internally shorted.
Can I keep driving?
The vehicle may restrict power or charging when cold because heater B may not preheat the battery correctly. Limit demanding driving and do not ignore worsening power loss or a red hybrid-system warning.
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.