Why is the Check Engine Light On?

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Why is the Check Engine Light On?

Why is the Check Engine Light On?It's one of those things that can make your heart sink in a moment's notice. The check engine light drives up fears of long trips to the auto shop and expensive repair bills. However, that isn't always the case. In most circumstances the check engine light is letting you know of a small problem that if addressed soon, will be an easy and affordable fix. However, the longer you wait, the worse the problem will get, as demonstrated by this first check engine light issue.

Catalytic Converter

The catalytic converter has a tough job, it turns hazardous exhaust fumes into less harmful emissions, and replacing it can be very expensive. Excessive gasoline fumes passing through the exhaust system could cause damage to it, an issue that could develop if one of the following two problems took place first, both of which would have triggered the light long before the catalytic converter was damaged.

O2 Sensor

The oxygen sensor rests in the exhaust system, monitoring the amount of oxygen within the exhaust fumes in order to calculate the proper air and fuel mix for the engine. A malfunctioning sensor can result in more gasoline being burnt than necessary.

MAF Sensor

The mass air flow sensor is similar to the oxygen sensor except it is placed at the front of the vehicle and monitors incoming air, measures it and determines how much of it needs to be mixed with the gas. If it malfunctions it too could cause excessive burning of gasoline, resulting in a loss of fuel efficiency and engine performance will suffer.


Misfiring is what happens when the spark plugs are not firing at the precise moment they need to for maximum efficiency and power. This can be a result of spark plug corrosion, worn ignition coils, bad spark plug wires and other issues. This will be a noticeable problem as it will cause your engine to run very rough.

Cracked Gas Cap

The best you can hope for is that you forgot to tighten the gas cap the last time you filled up. A loose, broken or cracked gas cap can allow for fuel vapors to evaporate out of the filler hose, causing the light to come on thanks to the EVAP system.

It is important to get the check engine light checked out by a professional auto repair shop as soon as it comes on to prevent issues from growing. If you need check engine light diagnostics in Corona, Riverside or the surrounding California communities be sure to visit Precision Import Auto Repair. Our full service auto repair shop handles all makes and models. To schedule auto repair in Corona call us at (951) 734-0795 today.

Precision Import Auto Repairs Blog

Written By Brian Corey

Published By MORBiZ

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