Cadillac STS Warning Lights: What They Mean

Red: stop or act now

Brake System Warning Light

There is a brake problem, or the parking brake is set or not fully released. Brakes may work poorly, with a harder or lower pedal.
What to do: Pull off the road and stop carefully. If the light stays on, have the vehicle towed for service. PDF page 244

Other warnings and indicators

Engine Coolant Temperature Warning Light

The engine is very hot. If it stays on while driving, there may be a cooling system problem and the engine could overheat.
What to do: See the Engine Overheating section and DIC messages for more information. PDF page 247

Antilock Brake System (ABS) Warning Light

If it stays on or comes on while driving, the antilock brakes need service. Regular brakes still work unless the brake warning light is also on.
What to do: Stop safely, turn the ignition off, restart to reset. If the light remains or returns, have the vehicle serviced. PDF page 245

Traction Control System (TCS) Warning Light

There may be a TCS problem, or the system was turned off with the button. While on, the system will not limit wheel spin.
What to do: Stop carefully, turn the engine off and restart. If the light persists, have the TCS inspected as soon as possible. PDF page 246

Low Tire Pressure Warning Light

Low tire pressure was detected. If it flashes about a minute then stays on, the TPMS has a malfunction and may not detect low pressure.
What to do: Stop as soon as possible and inflate the tires to the recommended pressure on the tire label. PDF page 412

Green: system on

Lane Departure Warning (LDW) Light

Green when the system detects a lane marking. It flashes amber with three beeps if a lane marking is crossed without a turn signal. PDF page 246

Summarized in our own words from the 2011 Cadillac STS owner's manual (AI-assisted; every light name was matched against its cited page 2026-10-18). Your vehicle may not have every light, and other years can differ. A red warning that stays on usually means stop safely and check: your manual has the final word.