The color code
Dashboard lights follow the logic of a traffic signal. Red means stop soon and safely. Amber or yellow means have something checked in the coming days. Green and blue only report that a system is on. Every warning light should glow for a second or two at startup as a bulb check, and one that never appears is itself a fault worth mentioning to a mechanic.
The red ones
- The oil can means that oil pressure has been lost. Pull over and shut the engine off at once, because an engine can destroy itself in under a minute without oil pressure.
- The thermometer in waves means that the engine is overheating. Stop, switch off and let it cool for at least thirty minutes, and never open a hot radiator cap, which can spray scalding coolant.
- The battery symbol means that the charging system has failed, usually the alternator or its belt. The car is now running on the battery alone, so turn off the accessories and drive directly to a shop, because you may have less than an hour.
- The brake light means first that the parking brake is on. If the brake is fully released and the light stays lit, the fluid may be low, and the car should not be driven until the brakes are checked.
The amber ones
A steady check engine light covers hundreds of possible faults, from a loose gas cap to a failing sensor. Tighten the cap until it clicks, and give the light a few days of driving to clear. A flashing check engine light is another matter. It signals an active misfire that is sending raw fuel into the catalytic converter, a part that costs well over a thousand dollars, so ease off the throttle and get to a shop promptly.
The horseshoe shape with an exclamation point is the tire pressure monitor, and it means at least one tire is roughly twenty-five percent below its proper pressure. The ABS light means the antilock function is off, although the ordinary brakes still work. An airbag or SRS light means the airbags may not deploy in a crash.
Getting the code read
A code reader plugs into a port under the dashboard and returns a code such as P0420. The code names the system at fault, not the part to replace, so treat it as the start of a diagnosis.
Note A traction control light that flickers on a slippery road means the system is working. Only a light that stays on steadily indicates a fault.
