Check Engine Diagnostics

Why Is My Check Engine Light On?

Ohhh No, the check engine light is on!… Nothing can make your heart stop quite like seeing your check engine light come on out of nowhere.

There are numerous reasons your check engine light can be triggered, but not all reasons are cause for panic. 

If your check engine light is on, schedule an appointment with us to run an engine diagnostic test. The cause of the issue should be recorded in your vehicle’s computer system. Once we diagnose the issue, we will let you know what’s involved to remedy the issue.

Below you will find common reasons why your check engine light comes on.

Schedule your check engine diagnostic test today, call 484-369-8342 or contact us.

Top 10 Reasons Your Check Engine Light Is On

Check Engine Diagnostics Kellys World-Class Auto Mechanic Services in Limerick PA. Serving Limerick, Royersford, Spring City, Collegeville, Pottstown, Schwenksville, and more.

The oxygen sensor, or aka O2 sensor, measures the amount of unburnt oxygen in a vehicle’s exhaust system. That level is used by your vehicle’s computer system to regulate the air-to-fuel mixture in the engine’s cylinders.

Although your vehicle will continue to run with a bad O2 sensor, the following damage/issues can occur:

  • Damage Spark Plugs
  • Damage Catalytic Converter
  • Burn Off More Fuel
  • Can Cause Emission Test Failure
  • Check Engine Light Is On

How Much Does It Cost To Replace An O2 Sensor? First, note that your vehicle may have more than one O2 sensor. The O2 sensor on its own can cost anywhere from $20 to $100 or more, depending on quality, and your vehicle’s make and model.  Labor hours will also vary depending on your vehicle.

It may sound silly that a gas cap can cause your check engine light to come on. However, a gas cap allows for correct gas tank pressure to remain stable. Also, a loose or missing gas cap allows fumes to escape the tank, costing you fuel and doing harm to the environment.

How Much Does A Fuel Cap Cost? Well, of all the check engine light issues, this may be the cheapest to remedy. Typically, a gas cap can cost roughly $10 to $60. 

Your catalytic converter is a crucial part of your vehicle’s exhaust system that protects the environment and your health.  A catalytic converter is responsible for turning the carbon monoxide produced by combustion, into carbon dioxide to be released into the environment. Just imagine being stuck in traffic and all vehicles were putting off carbon monoxide…

Also, a bad catalytic converter can cause your vehicle to fail emissions testing.

You will notice the title of this section has the word “missing”. Unfortunately, catalytic converters are a highly stolen item these days. If your vehicle’s check engine light came on due to the catalytic converter being stolen, we can get you back on the road, and submit through your insurance.

How Much Does A Catalytic Converter Cost? The cost of the part can roughly run from $300 to $2,500 or more. Although the part itself is very expensive, the placement of the catalytic converter is easily accessible in most cases, which helps with the labor costs.

How Can You Keep Your Catalytic Converter Healthy?

  • Regular Maintenance
  • Regular Oil Changes
  • Drive On Highways Often To Prevent Clogging.

A spark plug is pretty self-explanatory, it sets the spark to ignite the fuel and air mixture that are in the cylinders. The ignition coil is what generates the electricity that the spark plug requires to ignite the fuel and air mixture. If you have a gas engine (not diesel) your vehicle typically has one of each per cylinder, ex. 6 6-cylinder engine will have 6 spark plugs and 6 ignition coils.

Issues Caused By Bad Spark Plugs & Ignition Coils:

  • Engine Misfire
  • Acceleration Hesitation
  • Shuts Vehicle Off
  • Triggers Check Engine Light

How Much Does A Spark Plug Cost? Typically a spark plug costs $10 to a little over $25.

How Much Does An Ignition Coil Cost? Depending on the vehicle and the quality of the part, it can cost between $50 to $250, or more.

Most vehicles do have a battery warning light on the dash, but a dead battery can also trigger the check engine light to come on as well. If you jump the battery but your car continues to experience issues, you may need a new battery.

Have us install your new battery, as your vehicle may require codes to be entered after disconnecting and installing the new battery. Today’s vehicles have very advanced and sensitive computer systems that can be tripped simply by removing the battery, causing the check engine light to come on as well.

How Much Does A Car Battery Cost? A standard battery can run from $50 to over $120, a premium battery can run from $90 to over $200.

How To Take Care Of My Battery? Today’s batteries are much better, but you should stay very mindful not to leave your lights on, etc. And, driving your vehicle often will keep it from draining. Between security systems and other functions, the computer system may run even while the vehicle is “off”, so you should drive your vehicle once a week.

The mass airflow sensor, or MAF monitors/controls how much air enters your engine. This may sound odd, but especially with altitude changes, your engine will need more or less air intake. In the same way a human goes from sea level to mountain level, your breathing changes to take in more air to account for the diminished oxygen levels, your vehicle does the same.

What Are The Symptoms Of A Bad Mass Airflow Sensor?

  • Engine is difficult to start or turn over.
  • Engine stalls after starting.
  • Engine hesitation while driving or during idle.
  • Engine hesitation and thrusting while accelerating.
  • Irregular engine idling, high or low.
  • Reduced gas mileage
  • Check Engine Light Is On

How Much Does It Cost To Replace A Mass Airflow Sensor? The part can range from roughly $200 to $300, or more depending on your vehicle. Labor will be affected by how accessible the area is on your specific vehicle make and model.

Although most newer vehicles come with a comprehensive alarm system and option for car start, some people install these on older vehicles or upgrade on newer models. The same can be said for stereo/sound systems. Anytime you alter factory products that are tied to the vehicle’s electric system, there is the risk of issues. Especially, harming the vehicle’s computer system, which is very expensive.  

It’s very important to have a trained technician install aftermarket products. It may cost a bit more but it is well worth it.

Your vehicle’s vacuum system (like the word suggests) creates suction. This suction controls numerous vehicle functions such as monitoring emissions, regulating air-to-fuel mixture ratios, your brake system, HVAC, and transmission. 

Over time, vacuum hoses and fittings can become damaged from extreme heat and cold, causing them to dry out and crack.

What Are The Symptoms Of A Car Vacuum Leak?

  • Rough Idling
  • Difficulty Starting Vehicle
  • Increased Fuel Consumption
  • Performance Issues
  • Whistling Noise While Engine Running 
  • Check Engine Light On

How Much Does It Cost To Fix A Car Vacuum Leak? After diagnosing where the leak is coming from, the costs to fix a car’s vacuum leak can range between $150 to $1,000 and above, depending on parts affected and the make and model of your vehicle.

Did you know your engine’s combustion chamber can reach temperatures of 1,000 plus degrees?  Your engine needs to control that heat, and your exhaust gas recirculation valve does just that. 

Your exhaust gas recirculation valve (EGR Valve) should last about 10 years. However, issues can arise sooner and cause you to fail an emissions test.

Symptoms Of A Bad Exhaust Gas Recirculation Valve:

  • Poor engine performance, hesitation, stalling, or rough idling
  • Increased fuel consumption
  • Pinging or knocking sounds caused by increased temperature
  • Check Engine Light Comes On

How much does it cost to fix a bad (EGR Valve) exhaust gas recirculation valve? The parts run from $275 and up. Labor will depend on accessibility.

Your check engine light coming on due to bad oil or a bad tank of gas can be the cheapest fix to a check engine light. Modern cars come with so many sensors that are constantly monitoring for imbalances that can affect engine performance or cause engine damage. 

Dirty oil or lack of oil can cause your check engine light to come on to alert you, so you can remedy the issue and prevent further engine damage. A lack of oil in your car could be a signs of a leak or the engine excessively burning off oil.

We get it, gas is expensive and only seems to rise every year. However, if your vehicle requires high-test gas (typically 92 octane) and you choose a low-grade octane, your check engine light may come on. 

It’s tempting to save several dollars per fill-up by choosing a lower-grade fuel. But, your vehicle is manufactured to operate based on specific standards. Different grades of gas can burn at different temperatures, and explode in the combustion chamber at a different rate. Not using what is recommended can cause engine parts to not operate in the way they were built to, causing damage and lowering performance.

Schedule A Check Engine Diagnostic Check Today

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