Dashboard Warning Lights: What Red vs Yellow Means

Red vs yellow warning lights: what the colour tells you

The colour tells you how fast to act. Red means something is wrong right now and the car may be getting damaged, or may not be safe, as you drive. Yellow or amber means something needs attention soon. Green and blue are just information: headlights on, cruise set, high beams.

Ford's owner guidance lays it out about the same way. Red or orange means the vehicle has a problem and should be looked at promptly. Yellow means service may be needed. Other makers use the same logic, but the exact symbols and colours vary, so the warning-light page in your owner's manual is the final word for your car.

Two things that aren't problems. Almost every light on the dash flashes on for a second or two when you turn the key. That's the car checking its bulbs, and they should all go out once the engine starts. Some cars also show a blue thermometer on a cold morning. That just means the engine hasn't warmed up yet, and at -20 °C in a Dieppe driveway it may stay lit for a while.

The red lights that mean pull over now

Four lights mean find a safe spot and stop. Not at the next exit, not after you drop the kids off. Soon.

Oil pressure (an old-fashioned oil can). The engine isn't getting enough oil pressure, and without it the bearings and moving parts can be badly damaged in a short drive. Pull over and shut it off. Wait a few minutes and check the dipstick. Ford's guidance is clear that if the level is fine and the light still comes on, don't drive it. Some cars also have a yellow oil level light, which means top up soon. The red can is the serious one.

Engine temperature (a thermometer in wavy lines). The engine is overheating. Pull over, shut it off and let it cool. Don't open the radiator or coolant cap while it's hot, because the system is under pressure and the coolant can spray out scalding. A winter tell: if the heater suddenly blows cold while the temperature climbs, the coolant is probably low.

Brake (a circle with an exclamation mark, or the word BRAKE). Check that the parking brake is fully off first. If it is, the light usually means low brake fluid or a fault in the brake system. If the pedal also feels soft, don't drive. Our brake noise guide goes through the brake symptoms in more detail.

Charging (a battery shape). The alternator has stopped charging and the car is running on whatever is left in the battery. Ford's advice is to switch off everything electrical you don't need and get it checked right away. Heated seats, rear defrost and the blower on high all drain it faster. Head straight home or straight to wherever it's going to be fixed, and don't shut it off in the Champlain Place lot to run in for one thing. It may not start again. On a lot of engines the same belt that turns the alternator also drives the water pump, so if the temperature light joins in, stop.

The yellow lights that can wait a little

These don't mean pull over, but they don't mean ignore it for a month either.

Tire pressure (a horseshoe shape with an exclamation mark). This is the most common light we hear about on the first cold mornings of the fall in Moncton. Air pressure drops when the temperature does, and Cooper Tire's Canadian advice notes that cold weather alone can trigger the light without a leak. It may go out after a few kilometres as the tires warm up. That doesn't mean they're fine. It means they're low when cold, which is how they're meant to be measured. Set them to the pressure on the driver's door frame, not the number on the tire sidewall. Keep in mind the light comes on late. GM, for example, says its system warns when a tire is 25 per cent below the recommended cold pressure.

If the tire pressure light flashes for about a minute when you start the car and then stays on, that's usually the system itself reporting a fault, not low air. GM's owner info says the same. Here that very often means a second set of winter wheels that don't have sensors in them. It's not dangerous, but your early warning for a slow leak is switched off until spring, so check pressures with a gauge.

ABS (the letters ABS in a circle). Ford's guidance is that you still have normal brakes without the anti-lock function, unless the red brake light is on too. On ice that matters, because the wheels can lock in a hard stop. Leave more room and get it checked. The cause is often a wheel speed sensor or its wiring, which sit right out at the wheel with the salt and slush.

Traction or stability control (a car with squiggly lines behind it). If it flickers while you're pulling away on slush, it's working. Ease off the gas. If it stays on solid, the system has switched itself off, so drive like you don't have it. It often comes on with the ABS light because they share the same sensors.

Check engine (an engine outline). Solid means the computer has stored a fault, usually emissions or engine management related, and you should book a diagnosis soon. Flashing is different. Ford says a flashing light can mean the engine is misfiring and that continuing to drive may cut power or stall the engine. Ease off, avoid hard acceleration and get it checked as soon as you can. Unburned fuel from a misfire is also hard on the catalytic converter, which is an expensive part to cook. Our separate check engine light guide covers what happens next.

What to do the moment a light comes on

Before you do anything else, notice three things: the colour, whether it's solid or flashing, and whether the car feels different. A red light with steam, noise or a dead-feeling pedal is a stop-now situation. A yellow light and a car that drives normally is a phone-call-tomorrow situation.

Take a photo of the dash. It helps whoever looks at it later, especially if the light goes away and comes back.

The common mistake is clearing it. Unplugging the battery or using a cheap code reader to make the light go away wipes out information that helps find the real problem, and the light will usually be back in a few days anyway. A code reader is fine for curiosity, but a code tells you which system complained, not which part failed.

Getting a warning light checked without driving it in

The point of a red light is that you shouldn't be driving the car across town to a shop. That's where a mobile mechanic makes sense. We do on-site diagnostics in Dieppe, Moncton, Riverview, Shediac and around, in your driveway or your work parking lot.

Send us the vehicle, which light is on and your postal code through the form, or call or text (506) 871-0669. We call back, talk through what's going on and confirm the price before anyone drives out. If it turns out the job needs a hoist or shop equipment, we take it in and manage the repair through to the end.