When the check engine light in your car comes on, it gives you a sinking feeling and perhaps sends you into panic mode. The frustrating thing about this little light is that it could signal a minor problem which could take a few minutes to fix; or a serious mechanical problem which could take weeks and hundreds of dollars to fix.
There’s no way of knowing what it is. It is true that an illuminated check engine light could indicate any one of more than a hundred problems. On the other hand, there are some very common reasons why this light comes on. It is very likely that one of them is the reason your check engine light is on.
What Would Cause The Check Engine Light To Come On?
Faulty Mass Air Flow Sensor
Vehicles run on a mixture of gasoline and oxygen. The engine must maintain a tight gas/oxygen ratio for good performance. The function of the mass air flow sensor (MAF) is to regulate the amount of oxygen entering the system. A faulty MAF sensor causes the engine computer to miscalculate the amount of fuel required to run the engine.
As a result you are likely to experience problems starting the car, stalling or poor acceleration. Even if the car continues to run, a faulty MAF greatly reduces fuel efficiency. It can drop fuel efficiency by up to 25%. Changing the air filter regularly can help your mass air flow sensor last longer.
Failed Catalytic Converter
The catalytic converter is an integral part of the exhaust system. It serves to convert dangerous exhaust fumes produced by the engine’s cylinders into less harmful emissions released through the exhaust pipe. These converters respond to concerns around excessive pollution and the numerous negative effects on the environment.
The catalytic converter depends on receiving the expected combination of exhaust gases at the optimum temperature. Other malfunctions in the system which cause the temperature or mixture of exhaust gases to differ from the expected, could reduce effectiveness of the catalytic converter.
Faulty Ignition Coil
The ignition coil is a key part of a vehicle’s ignition system. It transforms the battery’s relatively low voltage (12V) to thousands of volts required to generate an electric spark in the sparkplugs to ignite the fuel. It is also called a spark coil. Typical signs of a failed ignition coil include rough idling, misfiring, stalling, reduced fuel economy and backfiring.
Can Low Gas Cause the Check Engine Light To Come On?
The check engine light can be triggered by a variety of malfunctions in the system. One of them is excessively high temperatures which are interpreted as overheating. Can an almost empty gas tank cause the check engine light to come on? Yes. It can. Here is why. The fuel pump in the gas tank relies on fuel to keep it cool. It should always be submerged in it.
When you constantly run your car on a low tank the fuel pump is not submerged so it could overheat and trigger the check engine light to come on. The best way to deal with this is to avoid letting your fuel tank go below quarter tank. Running the car with very small amounts of fuel also causes low fuel pressure which could also cause the light to illuminate.
Another reason low gas could cause the check engine light to come on is debris accumulated in the tank. When the tank is full, it is unlikely that accumulated debris would come into contact with the fuel filter. When the level is very low, some of this debris get into the filter and this could cause it to block. This in turn causes low pressure from the fuel pump.
Can Bad Gas Cause the Check Engine Light To Come On?
Would a bad tank of gas cause my engine light to come on? Yes. Your car has an inbuilt computer with numerous sensors which trigger the check engine light to come on as soon as it detects something abnormal, including emissions. If an abnormal amount of oxygen is detected in post- combustion emissions, it is recorded as a fault.
A vast majority of cars are designed to run on gas with ethanol content of 15% or below. It is based on this low ethanol content that the system is set to inject certain amounts of fuel into the engine at specific intervals. Adulterated gas contains higher levels of ethanol than required.
Once combustion takes place, the emissions contain higher levels of oxygen than expected. This difference in oxygen levels is detected and recorded as a fault.
If the gas is not bad enough to cause the car to stall, it continues to run albeit less efficiently. When the sensors detect higher levels of oxygen in the emissions, the system assumes that it is not injecting enough gas and increases the amount of fuel injected. It also re-adjusts the timing of fuel injection. You end up using much more fuel than you need to and this drastically reduces fuel economy.
How to Deal With a Tank of Bad Gas
You could end up with a tank of bad gas out of an honest mistake made by the supplier. An employee of the supplier could mix components in wrong ratios. A less common occurrence is when unscrupulous suppliers mix in water or other substances into the gas in an attempt to cut costs.
When you find yourself in this situation, take your car to a trusted repair shop so they can add a fuel octane booster like Dry Gas or Sea Foam to help ignite it. If you have a full tank of bad gas you may have to siphon it out then fill the tank with good clean gasoline.
Can low gas cause the check engine light to come on? Believe it or not, it actually can. Although the malfunction recorded will not point directly to low gasoline levels in the tank,it will be cleared as soon as the tank is filled. The best way to avoid this is to make sure gas levels never drop below quarter tank. This way the pump in the gas tank is kept sufficiently cooled and no debris can get into the filter.
Steven Reilly is a qualified mechanic and his passion for cars goes beyond just the technical aspects. He is also an amateur racer and all round car enthusiast. When he is not driving them, he can often be found in his garage under the hood of a rare model. Steven Reilly has lost track of the number of hours he has spent setting up his fine collection of rebuilt models. He believes that cars can provide a constructive and fun opportunity to teach the youth important life skills. In line with this, he is developing a community outreach program, potentially dubbed ‘Cars for change’.