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What to do If

Updated: Jul. 09, 2018

Expert advice on what to do if a dashboard warning light appears, plus how to prepare for and prevent other auto emergencies.

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What do you do if a dashboard warning light comes on? Our experts tell you how to respond to these and other common roadside emergencies. We also include tips on preventative maintenance that'll help avoid these troubles.

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Overview: “What to do if“ tips for warning lights, emergency kits and maintenance

Auto breakdown

Breakdowns don’t happen often, but it pays to know what to do if they do occur.

In a quick survey of coworkers and friends, I discovered that many people really don’t know what to do if a warning light appears on their dash. And they’re just as confused when it comes to which maintenance services are really important. So I’ve put together these tip lists for warning lights, maintenance services, driving advice and emergency kits. I guarantee you’ll find something here to help you be a safer, smarter driver and car owner.

What to do if warning lights come on

Dashboard warning lights

The warning lights flash on, then go off, when you start your car. If any remain on or come on while driving, follow our “what to do” guidelines below.

You’re driving down the road and your “HOT” light comes on. If your first thought is, “You’re hot? I’m sweatin’ bullets in here,” you’ve failed to understand the seriousness of the situation. Those warning lights aren’t a joke. If you ignore them and keep driving, you’re setting yourself up for major repair bills. In the items below we tell you what the lights mean and what you should do if any of them come on when you’re driving.

Warning light: TPS (Tire Pressure Sensor)

Tire Pressure Sensor light

The Tire Pressure Sensor light tells you that you have an underinflated tire.

At least one tire is low on air pressure. Fill it as soon as possible. Driving on an underinflated tire can cause a blowout, possibly resulting in an “at-fault” accident. Air is free (or cheap). But a new tire is about $125, and an accident will cost you your deductible and increased premiums in the future.

Warning light: Oil

Oil light

Stop in a safe spot when the oil light comes on and check the oil level in the engine.

The oil pressure is too low to keep driving. Pull over to a safe spot immediately. Check the oil level. If it’s low and you have oil on hand, add it and see if the light goes out. If you don’t have oil, call a tow truck or ask someone to make a roadside delivery. It’s better to spend $150 on a tow than $4,000 to replace a seized engine.

Warning light: Engine hot

Hot light

The hot light indicates engine overheating. Pull over in a safe spot and call for service.

The engine is overheated. Pull over to a safe spot immediately. Open the hood, then call a tow truck ($150 average tow to the nearest shop). If you keep driving, you can warp the cylinder head (minimum $1,000 repair bill) or completely destroy your engine.

Warning light: Battery

Battery light

You have a battery problem. Drive to the nearest repair shop for diagnosis.

Something is wrong with the battery or charging system. Turn off all high-load electrical accessories such as the air conditioning, heater fan and rear window defogger, and drive to the nearest shop.

Warning light: Flashing “Check Engine”

Check Engine light

When the Check Engine light flashes, pull over to a safe spot and call for service.

The computer has detected a misfire serious enough to damage your catalytic converter. Pull over to a safe place or drive to the nearest exit and call a tow truck. Get the underlying misfire problem fixed right away—a new catalytic converter can cost $1,500.

Warning light: Steady-on “Check Engine”

Steady-on Check Engine light

When the Check Engine light comes on, make a service appointment to have it checked out.

The computer has detected a problem with the engine or the emissions system. If the vehicle is running fine, you don’t have to rush in for service. But if it’s running rough, stalls, hesitates on acceleration or gets poor gas mileage, make an appointment to get it checked out sooner rather than later.

5 Maintenance tips: What to do to keep your engine running

Shops recommend 30,000-, 60,000- and 90,000-mile services that can easily cost $400. The majority of the items on those lists are inspections. Sure, they’re important, but the “replace” items are the most important. Here are the top five items you must replace in order to avoid major repair bills later.

1. Transmission fluid
If you put on 200,000 miles during the life of the car, you’ll spend about $800 on fluid changes. If you skip the fluid changes, you’ll only have $800 to put toward the $2,000 cost for a transmission rebuild. Did you buy an extended warranty? Well, you just voided that, too. It never pays to skip this service.

2. Coolant
If you change the newer long-life coolants twice over a 200,000-mile period, you’ll spend $300. If you don’t change it, plan on spending about $1,800 on a new radiator, heater core and water pump. Kiss the extended warranty goodbye, too. For best results, always use genuine factory coolant.

3. Oil filter
You already know how important oil changes and synthetic oil are to the life of your engine. But an extended-life oil filter is just as important. They cost about $10 but are rated to last 7,000 to 10,000 miles. Economy filters start to clog and self-destruct after about 4,000 miles. Once the filter media disintegrates, it can spew debris into critical parts and cause thousands in repair bills.

4. Spark plugs
Newer-style platinum/iridium spark plugs are rated for 100,000 miles. But they start misfiring at about 80,000 miles. Misfires damage spark plug wires, ignition coils, ignition modules and sometimes even your catalytic converter. If you don’t change the plugs, you can count on a minimum of $400 in ignition system–related repairs.

5. Timing belt
A broken timing belt will leave you stranded (if your engine has one). If you’re lucky, you’ll just have to pay $150 for a tow and then $600 (parts and labor) for the new belt. But if you have a certain type of engine (called an “interference” engine) and the belt breaks while you’re driving, it’ll destroy your engine, costing you about $4,000.

Regular Service Items to Avoid Future Engine Trouble

Following the service manual maintenance guidelines will help avoid trouble caused by dirty engine fluids and spark plugs.

What to pack in an emergency kit

If you follow every expert’s advice on what to carry in the event of an emergency, you’d have a trunk full of supplies (especially candy bars). I’m not disputing the value of carrying all those items, but I don’t know anyone who does. So I’ve assembled a list of “must-have” items that take up very little space and can really help you in an emergency. To help you remember these items, clip this section and stuff it in your glove box.

  • Pad/pencil for accident information
  • Air compressor to inflate your spare tire
  • Duct tape to use as a handyman bandage or to reattach vehicle parts after an accident
  • Cell phone charger to keep your cell phone running until help arrives
  • LED headlight so you can use both hands while you fix a flat tire, add oil, etc.
  • Oil to refill your engine if it’s critically low from leaks or excessive consumption
  • Jumper cables to get you going again and right to a service station
  • A can of Fix-A-Flat (about $8) to fix a flat tire when the wheel is rusted in place and won’t come off

Auto emergency kit

Keep this collection of “must-have” items in your car for emergencies. Add others that meet your local weather conditions and sense of security.

Additional emergency gear: Cold weather clothing

If you’ve ever changed a tire in the dead of winter, you know how quickly your hands get numb from working with subzero tools. And winter winds can freeze your ears in seconds, making you unable to even finish the job. Frostbite is a serious risk. If you pack nothing else in your winter emergency kit, make sure you at least have warm gloves and a hat that covers your ears.

Tip from reader Tim Boehnen:

“No one taught me how to change a flat tire. So I had to change my first flat on the side of a busy road at dusk. I almost got hit four or five times. Now, I’ll make sure all of my kids change a tire BEFORE they get any keys.”