Vehicle Warning Lights: What Each One Means and Costs

A colour-coded guide to vehicle warning lights, what each symbol means, which ones mean stop now, and realistic repair costs to expect.

Vehicle warning lights are your car's first and most honest attempt to tell you something is wrong, yet most drivers only recognise a handful of the twenty or more symbols that can appear on a modern dashboard. Knowing the difference between a light that means "book a service soon" and one that means "pull over now" can save you from a roadside breakdown, a wrecked engine, or a repair bill several times larger than it needed to be. This guide explains the colour-coding system, decodes the symbols you are most likely to see, and shows you how to respond to each one sensibly.

The colour code: red, amber and green

Every manufacturer follows the same broad traffic-light logic, so the colour of a symbol tells you how urgent it is before you even identify the shape.

• Red means stop or act immediately. A red light indicates a serious safety risk or a fault that can cause rapid, expensive damage - loss of oil pressure, overheating, a charging failure, or a brake problem. Treat a red light as an instruction to pull over safely and investigate.
• Amber or yellow means something needs attention soon but is not usually an emergency. The car has detected a fault or a system operating outside its normal range. You can often drive gently to a garage, but do not ignore it.
• Green or blue is purely informational - it simply confirms a system such as headlights, indicators or cruise control is switched on.

When you first turn the ignition on, most lights illuminate briefly as a bulb check, then go out once the engine starts. A light that stays on, or comes on while driving, is the one that matters.

The warning lights that mean stop now

A small group of red lights should never be driven on. If any of these appear and stay lit, bring the car to a safe halt as soon as you can and switch off the engine.

The oil pressure and temperature lights are the two most dangerous to ignore. If either appears, stop, switch off, and do not restart until the cause is found - continuing even a short distance can turn a minor fault into a full engine replacement costing $3,000-7,000 or more.

The amber lights you can usually drive on - carefully

Amber lights give you room to plan rather than panic, but each still points to a genuine fault.

• Check engine light (engine management light): A steady amber engine outline means the engine control unit has logged a fault, anything from a loose fuel cap to a failing sensor or misfire. If it is *flashing*, an active misfire is dumping raw fuel into the exhaust and you should ease off and get it checked quickly to protect the catalytic converter. You can look up the exact fault behind this light with our OBD-II code lookup.
• ABS light: Your anti-lock braking system has faulted. Normal braking still works, but the anti-lock function may not, so brake gently and avoid emergencies. Do not confuse this with the red brake light.
• Tyre pressure (TPMS): One or more tyres are low or losing pressure. Check and inflate them; a light that returns quickly suggests a slow puncture.
• Traction control / stability (ESP): Flashing means the system is actively working in slippery conditions; staying on means it has switched off or faulted.
• Glow plug (diesel): A coiled amber symbol on diesels is normal for a few seconds when preheating. If it stays on or flashes after starting, it signals a preheating or engine fault.
• Airbag / SRS: The supplemental restraint system has a fault and airbags may not deploy in a crash - a safety issue worth prompt attention.

How to respond when a light appears

A calm, methodical response beats guesswork every time. Follow these steps when a warning light comes on unexpectedly.

1. Note the colour. Red means find a safe place to stop; amber means keep monitoring and plan a garage visit.
2. Check the basics. For a red oil or temperature light, look at the oil level on the dipstick and the coolant level once the engine has cooled. For a check engine light, make sure the fuel cap is fully tightened - a loose cap is a surprisingly common trigger.
3. Watch the gauges. Confirm what the light is telling you against the temperature gauge or any digital readouts. A genuinely overheating engine will show a rising needle.
4. Scan for the fault code. For any amber engine or emissions light, plug in an OBD-II reader. The code narrows the cause from dozens of possibilities to one or two. Our free car tools include a symptom checker to help you interpret what you find before booking a garage.
5. Decide: drive or stop. If a red light is confirmed by the gauges, stop and call for assistance. If it is a steady amber light and the car drives normally, book a diagnosis within a few days.

What diagnosis and common fixes cost

The light itself is only a pointer; the real cost depends on the underlying fault. These are typical ranges to set your expectations.

A professional diagnostic scan usually costs $80-150 and is money well spent - it prevents the classic mistake of replacing parts one by one. Many garages deduct the scan fee from the repair if you go ahead with them.

Clearing a warning light the right way

It is tempting to make a light disappear, but the method matters. Disconnecting the battery or using a scanner to erase a code only hides the symptom - if the fault remains, the light returns within a few driving cycles, and you may have wiped useful freeze-frame data in the process. The correct sequence is to diagnose the fault, repair the underlying cause, then clear the code and confirm it stays off after a test drive. If a light keeps returning after a repair, the original diagnosis was likely wrong. For deeper reading on decoding engine faults specifically, see our guide to engine misfire symptoms.

For any red safety-critical light involving brakes, steering, oil pressure or overheating, have a qualified mechanic confirm and carry out the repair rather than risk driving on a compromised system.

Frequently asked questions

Is it safe to drive with the check engine light on?

If the light is a steady amber and the car drives, accelerates and idles normally, you can usually drive to a garage within a few days. If the light is *flashing*, or the car is running roughly or losing power, stop driving hard and get it diagnosed promptly - a flashing light signals an active misfire that can destroy the catalytic converter and lead to a repair costing several hundred dollars or more.

Why did a warning light come on and then go off?

An intermittent light often points to a fault that appears only under certain conditions - a sensor playing up when hot, a loose connection, or a tyre near the pressure threshold. Even though the light has gone out, the fault code is usually stored in the ECU. Scan the car with an OBD-II reader so you can address the cause before it becomes a permanent, and possibly worse, problem.

Can I turn off a warning light myself?

You can clear most amber fault codes with an inexpensive OBD-II scanner, but only do so after fixing the underlying cause. Simply erasing the code, or disconnecting the battery, does not repair anything - the light will return once the car detects the same fault again, and you will have lost the diagnostic data that helps pinpoint it.