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Speedy Wrench is your Citrus County local auto service provider. From oil changes to engine swaps, we maintain, service and repair all makes & models. Call us or drop in.
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Today’s vehicles use technology to increase performance, while decreasing fuel consumption and the regularity of needing a tune up. However, the ability of your car’s computerized control system is limited when the sensors and components that deliver information don’t function properly.

Many different things can trigger the check engine light. Even a loose gas cap. The check engine light is just a light telling you that there is a problem, but NOT what that problem is.

Why is my check-engine light on?

Unless your car starts smoking, or stalls completely, bring it to SPEEDY WRENCH and have one of our qualified service technicians run a diagnostic to find the issue. We’ll connect our computers to your car’s OBD connector and analyze the codes that it returns. Those codes are the starting point for fixing your car’s problems.   If your vehicle won’t start, we can even tow it in for you.

Issues that can trigger the check-engine light are:

  • A faulty sensor or A/C evaporator system leak
  • Faulty oxygen sensors
  • Worn-out spark plugs, wires or direct ignition coils
  • Loose or cracked hoses or manifolds
  • Sticky exhaust gas recirculation valves
  • Pinched or deteriorated fuel injectors
  • In need of a tune up

Check to make sure your gas cap is on and give it a few more clicks to tighten it up. If that doesn’t work, head to Speedy Wrench, it’s always a good idea to get a professional to diagnose the problem.  A few of the above items are inexpensive to fix. While others are more expensive, it’s still important to get them taken care of. Even though the car could be driving just fine, you may be wasting fuel, putting out lots of pollution and damaging the engine. One sign of immediate attention is if the check engine light is flashing on and off. This is telling you that the problem is in need of urgent attention before major damage is done.

Whatever you do, don’t lazily slap a piece of black electrical tape over it and go about your business. Cars just need a little love from time to time to stay in good shape, and neglecting a minor issue could lead to bigger problems down the road.


Five common malfunctions cause the check engine light to come on:


One: Replace Oxygen Sensor

An oxygen sensor is a part that monitors the unburned oxygen from the exhaust. It helps monitor how much fuel is burned. A faulty sensor means it’s not providing the right data to the computer and causes a decrease in gas mileage. Most cars have between two and four oxygen sensors.

What causes it: Over time, the sensor gets covered in oil ash and it reduces the sensors ability to change the oxygen and fuel mixture. A faulty sensor not only reduces gas mileage, it also increase emissions.

What you should do: Not replacing a broken oxygen sensor can eventually lead to a busted catalytic convertor which can increase cost of repairs


Two: Loose or Faulty Gas Cap

You wouldn’t think a gas cap would be that important, but it is. When it’s loose or cracked, fuel vapors leak out and can throw the whole fuel system off. This causes a reduction in gas mileage and increases emissions.

What causes it: If you get an error pointing to the gas cap it means fuel vapors are leaking out of your cap. This means the cap is either cracked or just wasn’t tightened well enough.

What you should do: If your car isn’t feeling jerky or strange when the check engine light comes on, first you should check that the gas cap is on. Pull over, re-tighten it, and take a look at the cap to see if it has any cracks in it. Continue driving and see if the check engine light turns off.   If tightening the gas cap does not resolve the issue, come to SPEEDY WRENCH to diagnose your problem.


Three: Replace Catalytic Convertor

The catalytic convertor works to reduce exhaust gases. It converts carbon monoxide and other harmful materials into harmless compounds. If your catalytic convertor is failing, you’ll notice a decrease in gas mileage or your car won’t go any faster when you push the gas.

What causes it: Catalytic convertors shouldn’t fail if you’re keeping up on regular maintenance. The main cause of failure is related to other items on this list, including a broken oxygen sensor or deteriorated spark plugs. When it fails, it stops converting carbon monoxide into less harmful emissions.

What you should do: If your catalytic convertor fails completely, you eventually won’t be able to keep the car running. Your gas mileage will also be terrible, so you should try and fix it as soon as you can.


Four: Replace Mass Airflow Sensor

The mass airflow sensor tells the car’s computer to add the proper amount of fuel based on the air coming through to the engine. A faulty one can increase emissions, cause the car to stall, and decrease gas mileage.

What causes it: Most mass airflow sensors fail because of an improperly installed (or never replaced) air filter. You should replace the air filter at least once a year to help prevent the airflow sensor from failing.

What you should do: You will notice a decrease in gas mileage and over time the car will eventually start stalling a lot bring it in to Advanced Auto Diagnostics and we will let you know what the most cost effective solution is.


Five: Replace Spark Plugs and or Ignition Coils

The spark plug seals the combustion chamber and provides a gab for a spark to jump across and initiates combustion in your engine. When the Ignition Coils are failing, the spark plugs misfire. You’ll feel a little jolt in your car’s acceleration when this happens and lack of power. In some vehicles the vehicle will go into a safe mode and indicate lack of power in order to prevent damage to the engine and catalytic. Check engine light might also start flashing on and off.

What causes it: Most spark plugs in cars should be replaced every 25,000 to 100,000 miles depending on the type of plug used. Still, plugs fail over time and there’s not much you can do about it. More common are direct ignition coils that fail to send the electrical power through the spark plug.

What you should do: Get them replaced right away. If your spark plugs fail and you’ve made your way to SPEEDY WRENCH, have them checked to determine the proper course of action to repair.

Plenty of other possibilities for a check engine light are out there, but the above five are the most common.


The Speedy Wrench diagnostics department has the experience and know-how to find the issue and fix the problem… but you can probably tighten your gas cap yourself.