Modern cars communicate through symbols, and the colour is the first thing to read. It's a traffic-light system hiding in plain sight.
The three reds that mean stop now
If any of these appear while driving, find a safe spot and switch off the engine. Continuing can turn a manageable repair into a very expensive one.
Oil pressure (the oil-can symbol)
A red oil-can symbol means the engine may not be getting enough oil pressure. Running an engine without pressure for even a few minutes can destroy it. Stop, switch off, and check the oil level once the engine has cooled.
Engine temperature (the thermometer in waves)
Red means the engine is overheating — most common in summer traffic or when towing with a weak cooling system. Pull over, switch off, and wait. Never open the expansion tank cap on a hot engine.
Battery / charging (the box with + and −)
If this red light stays on while driving, the alternator likely isn't charging. You're now running on the battery's reserve alone. Head straight to a garage before the car cuts out completely.
The ambers worth understanding
- Engine management (the engine outline): a broad signal. Steady amber means get it scanned soon; flashing means a misfire — ease off and head in.
- ABS: your normal brakes still work, but the anti-lock system is offline. Brake gently and get it checked.
- Tyre pressure (TPMS): a tyre is low. A frequent and easily fixed warning, especially as the weather turns cold.
- Brake system: could be the handbrake left on, low brake fluid, or worn pads. Never ignore it.
Lights that are just information
Green and blue symbols aren't warnings at all. Green usually means a system is active — headlights, indicators, cruise control. Blue almost always means the main-beam headlights are on. No action needed beyond the courtesy of dipping your beams for oncoming traffic.
Half the panic calls we get are about blue or green lights. The other half waited two weeks on a red one. People have it exactly backwards.
Raj Patel, Diagnostics Lead