Top 10 Causes Why Your Car Check Engine light is on?
Below are the top ten most likely reasons that glow the check engine light of your car
Finally, the vehicle health check index has been released and we managed to get a big chunk out of it to discuss the reasons that what are the factors that trigger one of the most dangerous warning light on the instrument cluster? If not tackled quickly, a minor issue can end up in you buying a replacement car engine or getting it reconditioned.
We have populated top ten reasons and in more than 90 percent vehicle, when check engine light glows, more than 9 times out of 10, one reason out these ten held responsibly. Average costs of repairing these error codes vary dealer to dealer and garage to the garage because now labor costs have been increased to a certain level in the UK and there are many things involved in repairing the different error codes and them source different tools and expertise from vendors.
These engine errors trigger more often as the engine life of the vehicle increases and aging affects the performance of the vehicle. The chances of glowing engine light increase by 50 to 60 percent when a car aged 10 years or older. According to a car data handling firm in the UK, more than 10 percent vehicles of the model year 2006 and 2007 need repair works and according to last year’s data across the UK 15 percent vehicles of the model year, 2006 faced the check engine light issue. The vehicle aging factors change the type of repair and type of error codes triggered with the passage of time and they increase repair bills accordingly. Average repair cost can vary from £300 to sometimes over thousand, depends on the situation and error code. Let’s see what are the top ten possible reasons that trigger your check engine light warning light?
10 – EVAP Purge Solenoid Replacement

Why Your Car Check Engine light is on?
This is a module that controls the emissions of a vehicle and controls the fuel vapors from flowing into the air and damage the air. According to the report, this error was very limited in the past but now when automakers are applying strict procedures to control emissions, these errors start building on a massive scale. The EVAP modules come directly under the control of the ECU or engine control unit, in some models powertrain control unit controls the operations of these units. They usually work on a duty cycle and mostly left open and face faults. This way ECU triggers the check engine light on your instrument cluster dashboard. On average, this error code costs you £300 or even more depends on the state of the error.
9- Evaporative Emission Purge Control Valve

This is another situation where engine light glows up and this time EVAP purge control valve involved. The central computer system of the vehicle controls purge control valve. When the engine is fully warmed up and started working, this system activates the EVAP purge valves and the engine computer starts gradually starts sending the fuel vapors from charcoal chamber to the engine combustion system so that they can be ignited in the chambers. But if the engine computer feels that this flow of moving fuel vapors is disturbing the processes and moving less or more than expected by the engine computer, it turns the engine light ON.
Sometimes, the EVAP valves also get stuck and stopped controlling the flow of the fuel vapors, causing a replacement of the valve module.
- Spark Plugs and Wire Replacement

The spark plugs are an important part of the petrol engines, they help ignition system by charging the mixture of fuel and air coming into the combustion chambers. Spark plugs consist of plugs itself and spark plug wires if any of these two stopped working or face any kind of fault, the engine light will turn ON. On the other hand, faulty spark plugs reduce the fuel economy of the vehicle because they do not properly ignite the fuel, cause serious misfiring and do not allow the fuel burning to its best. This fuel then transferred to the catalytic converters and stuck them.
The spark plugs are not a kind of repair that you need to take your vehicle to the garage. You can change them yourself at home. They usually cost under £20 but if the wires of the spark plug involved, you must go to your garage and ask them to check the wires and replace if damaged.
- Damaged Mass Air Flow Sensor

The Mass Air Flow sensor actually senses the amount of the air coming into the engine chambers and determines the actual amount of fuel to be sent to the engine’s ignition and combustion chambers. The malfunction of the Mass Air Flow sensor it drops the fuel economy to more than 25 percent and ultimately damages the spark plugs and other precision parts. Damaged Mass Air Flow sensor also turn the engine light ON and it is not an easy replace like you can do on spark plugs, it involves technical experience and expertise. The replacement if these sensors is also a bit expensive but again the prices depend on the condition of the error.
- Ignition Coil(s) malfunction

The ignition coils in an engine’s combustion system play a vital role by distributing the combustion sources to combust the fuel and air mixture in the engine. These coils take electric current from the battery and pass it over the spark plugs to initiate the ignition system. Sometimes, spark plugs failure or the malfunction of the spark plug wires can damage the coils and this situation turns the check engine light ON. This does not only spark plug wires that can cause malfunction but the engine bay temperature and age factor also play a vital role.
If ignition coils failed, they can cause a serious damage to catalytic converters and other parts of the car as well, so, they must be treated properly and on time.
- Engine Thermostat failure

Why Your Car Check Engine light is on?
The thermostat is one of the most important parts of the engine and regulates the engine coolant temperature or the engine temperature. It opens and closes the coolant as needed and regulates the engine temperature to warm and cool the engine. Usually, when thermostat fails, it gets stuck in open position and stops controlling the engine temperature. Now the engine computer which is regulating the operations, senses that the engine temperature is not increasing to the operating temperature at the certain time, it turns the check engine light ON.
Car thermostats come under direct contact with coolants thus face serious rusts and scalps and stopped working after some certain period. It is recommended that you must swap the thermostats on some recommended mileage intervals.
- Tighten or Replace Fuel Cap

Why Your Car Check Engine light is on?
Fuel caps can also trigger the check engine light, Amazed? Don’t need to be, because it is fact that an extra tighten fuel tank cap or even a missing fuel tank cap in most modern vehicle turns the check engine light ON. These repairs usually count for 4 percent of total repairs. Missing fuel caps or damaged fuel caps can cost time more than money. They also cause hassle and stress that why check engine light is turned ON. The loosen fuel tank caps damage the environment by evaporating fuel into the air and reduce the fuel economy to some extent as well. At the same, luckily it is one of the cheapest repairs.
- Ignition Coil(s) and Spark Plug(s) malfunction

Why Your Car Check Engine light is on?
We have discussed spark plugs and spark plug cables, we also discussed the ignition coils and electrical source but this combination is one of the rare and expensive repairs that can lead to more damages. But at the same time, it is one of the most common repairs and counts for more than eight percent of total vehicle faults. These repairs are bit technical as ignition coils involved and they must be handled by technical experts to save your time, money and increase the performance of your car.
- Catalytic Converter failure

Why Your Car Check Engine light is on?
The catalytic converters in the petrol engines and DPF filters in the diesel engines control the carbon emissions. The functionality of these modules comes under direct control of the Engine Control unit. If they cause any irregularities in the functions, the ECU turns the CHEK ENGINE light ON. The catalytic converters are expensive repairs and they usually won’t fail unless the misfire occurs. The DPF filters usually fail when sudden temperature changes occur on rainy days. The catalytic converters can cause serious engine problems when blocked or damaged.
- Faulty Oxygen Sensor

The oxygen sensor replacement is one of the most common repair counting for more than 10 percent of total causes of turning the check engine light ON at your vehicle instrument cluster dashboard.
The Oxygen sensors are the vital parts and play an imperative role in the engine performance as well as help protecting the environment. They measure the unburned amount of air in the exhaust and inform the computer if the unburnt air amount exceeds the certain level which is not suitable for ideal ignition.
Such kind of situations arise when people ignore regular oil changes and internal coolant leaks occur. They cause more than 40 percent reduction in the fuel economy and replacement is expensive than any average repair.

