BYD high-voltage battery warning light: what it means
What the high-voltage battery fault and overheating warning lights mean on BYD EV and DM-i models, and when to stop the vehicle.
Safety and service note
What this means
BYD's official owner handbook describes two related high-voltage battery lights: a fault warning light that comes on when the ignition is switched on and should go out within a few seconds if the system is healthy, and a separate overheating warning light. If the overheating light comes on steadily, the battery temperature is too high and the vehicle must be stopped to cool down; if it flashes, the handbook recommends stopping safely and leaving the vehicle as soon as possible.
What causes it
The handbook lists driving up a slope for a long time in hot weather, long periods of stop-and-go traffic, frequent rapid acceleration or hard braking, and running the vehicle for a long time without pause as conditions that can lead to high-voltage battery overheating. A steady fault light unrelated to heat points to a genuine system fault rather than driving conditions.
What to do
If the overheating light flashes, stop the vehicle safely and get away from it as soon as possible, then contact BYD roadside assistance or an authorised service provider. For a steady fault-warning light, avoid driving the vehicle and contact a BYD authorised dealer or service provider to check the problem as soon as possible. Never attempt to inspect, cool, or work on the high-voltage battery yourself.
Important
If the overheating light flashes, stop the vehicle safely and get away from it as soon as possible, then contact BYD roadside assistance or an authorised service provider. For a steady fault-warning light, avoid driving the vehicle and contact a BYD authorised dealer or service provider to check the problem as soon as possible. Never attempt to inspect, cool, or work on the high-voltage battery yourself.
Frequently asked questions
What is the difference between the fault light and the overheating light?
The fault warning light indicates a general high-voltage battery system problem; the overheating warning light specifically indicates the battery temperature is too high.
What should I do if the overheating light flashes?
Stop the vehicle safely and move away from it as soon as possible, then contact BYD roadside assistance or an authorised service provider -- do not wait or continue driving.
What conditions can cause the high-voltage battery to overheat?
Long uphill driving in hot weather, extended stop-and-go traffic, frequent rapid acceleration or hard braking, and prolonged driving without a break are all listed in the official handbook as contributing conditions.
Can I keep driving if only the fault light is on, steady, without overheating?
The handbook recommends avoiding driving and contacting BYD service as soon as possible rather than continuing normal use.
Is it safe to check or cool the high-voltage battery myself?
No. The high-voltage battery is part of the vehicle's high-voltage system and must only be inspected or serviced by an authorised BYD technician.
Does this apply across the BYD range?
Yes -- high-voltage battery warning-light behaviour is described consistently across BYD's current EV and DM-i owner handbooks, though the exact wording can vary slightly by model.
Sources for this guide
This guide is for informational purposes only. Always consult an authorised service centre for safety-critical repairs. AutoTechHelp is not liable for any damage resulting from the use of this information.