Auto Start-Stop / Mild Hybrid Warning
Informational — For your awareness
What It Means
The auto start-stop system or mild-hybrid system has a fault or has been temporarily disabled. This system automatically shuts off the engine when stopped and restarts when the brake is released to save fuel.
Common Causes
- 12V auxiliary battery degraded (start-stop vehicles use AGM or EFB batteries — need replacement)
- Hood not fully closed (safety interlock for start-stop)
- Engine not at operating temperature (normal — system re-enables when warm)
- Cabin climate demand too high (normal in extreme weather)
- Auxiliary battery or DC-DC converter fault (mild hybrid)
Can I Still Drive?
Yes — the vehicle operates normally, just without automatic engine stop/start. The most common cause is an aging 12V battery that no longer meets the start-stop spec. Replace with an OEM-spec AGM battery.
Estimated Repair Cost
$150 – $500
This is an estimate only. Actual costs vary by vehicle make, model, year, location, and shop labor rates. Always get multiple quotes for major repairs.
Related OBD-II Trouble Codes
These OBD codes are commonly associated with this warning light. Scan your vehicle with an OBD-II scanner to get the exact code before diagnosing.