5 Car Warning Lights You Should Never Ignore

Car Warning Lights

Ignoring warning lights is an easy way to cause major damage to your car, or can lead to a breakdown or accident. Do not ignore any of these warning lights!


The oil pressure warning light is an indicator that your oil pressure is low or that you engine has lost oil pressure completely. If this light comes on, immediately pull over, turn the car off, and check the oil level using the engine dipstick.

Possible causes include lack of oil (due to oil consumption or leaks), oil viscosity being too thin, a worn out oil pump, excessive engine bearing clearances or a defective oil pressure sending unit.

If the engine is making noises such as ticking, clattering, or rapping, the noises indicate that the engine is not getting sufficient oil. If you continue to drive the car in this condition, you will probably damage it.


The temperature warning light is an indication of your engine overheating. Under no circumstances should you continue driving if you engine is overheating! This can lead to expensive engine damage such as piston scuffing, valve stem galling, failed head gasket, cracks, or distortion in the cylinder head. If you engine is overheating, you should check the radiator and heater hoses, and check the radiator and engine for coolant leaks. Be sure to check the level of coolant in the reservoir.

A word of caution: DO NOT open the coolant reservoir or radiator cap until the engine has had sufficient time to cool off, at least 30 minutes, or the pressure inside the cooling system can cause steam to blow out and burn you!

If your coolant level is low, add coolant (a 50/50 mixture of antifreeze and clean distilled water) after the engine has cooled down.

Possible causes of the temperature warning light coming on include a low coolant level (due to coolant leak or bad head gasket,) stuck thermostat, bad water pump, broken serpentine belt, defective radiator cooling fan, clogged or dirty radiator, exhaust restriction (plugged catalytic converter).

Turning off the air conditioner and turning the heater to high may temporarily help cool down an engine that is overheating due to hot weather or added strain from towing a trailer. However, if the engine is running hot because it is low on coolant, this won’t help much.


The “GEN” or “ALT” warning light, or an icon of a battery is the indicator that the charging voltage of your battery is low. While you don’t have to stop immediately for this one, you should be aware you may only have 20-30 minutes of driving time before your battery dies and you car stops. Anything on such as radio, AC, or headlights can shorten the time that you have.

Possible causes of this warning like are a broken or slipping serpentine belt or V-belt, bad alternator, charging control fault, or loose/corroded battery cables.

You should check the drive belt that turns the alternator to make sure it is intact and is turning the alternator while the engine is idling. If the belt is not the problem, chances are the charging system has a problem that will have to be diagnosed and repaired.


The brake warning light comes on if the parking break has not been fully released, but can also indicate the brake fluid level is low or there has been a loss of hydraulic pressure in one of your car’s brake circuits. Loss of fluid or brake pressure means the brakes may not be able to stop your car when you step on the pedal.

Carefully apply the brakes to make sure they are working. If they do still work, pull over and check the fluid level in the brake master cylinder. If the fluid level is low, you should check the brake system for leaks. Any leak means you should not be driving!

If the brake pedal is low or goes to the floor, you should pump the pedal as that may apply enough pressure to stop your car. In the event that fails, you can apply your parking brake to slow your vehicle. You can also try shifting to neutral or downshift to use engine braking to slow your vehicle.

Possible things that can cause this warning to come on are loss of brake fluid due are leaks (master cylinder, calipers, wheel cylinders, brake lines or hoses,) failure of the pressure differential switch that activates the brake light, parking brake pedal or handle not fully releasing, or defective parking brake switch.

If the brake pedal feels soft, is low, goes to the floor, or you have to pump the pedal to get your vehicle to stop, your vehicle is unsafe to drive. You should have it towed to a repair facility for repairs.


The low tire pressure warning light indicates that a tire on your vehicle is 25 percent or more under-inflated. Driving on a low tire can lead to a blowout. A low tire can also cause uneven braking, uneven traction, uneven and rapid tire wear, increased rolling resistance and fuel consumption.

Find a gas station with an air pump, and check the inflation pressure in each tire with an accurate gauge (not the gauge on the pump, which is often very inaccurate!). Add air as needed to inflate your tires to the recommended pressure (see your owners manual or the tire inflation decal in the door jam or glove box). For most passenger cars, the recommended pressure is typically 32 to 34 PSI.

The low tire warning light can be caused by loss of air pressure due to a leak (such as a nail or small puncture in a tire, or a bad valve stem), loss of air pressure due to seepage (1 to 2 PSI per month loss is normal for many tires), or inaccurate or failing TPMS sensor in tire.

Checking your tires regularly (at least once a month or before any long road trip) is recommended. Check the tires when they are COLD and BEFORE you drive your vehicle as driving creates friction and heats up the tires (causing an increase in air pressure).


Many vehicles have their own unique warning lights or icons that alert you when something is wrong. You can find these in the back of your vehicle owners manual. If you need to have a warning light checked out in Williamston, come see us at Rob’s Auto & Diesel Repair, call (252) 792-9997.