what causes service engine light to come on

While your machine can't talk, it communicates with you using chimes, icons, and letters. One icon that y'all should never ignore is the orangish, engine-shaped one that is normally establish in the instrument cluster. Information technology turns on when the car's onboard reckoner detects a problem.

Don't panic if you lot encounter it — it doesn't necessarily mean you'll need to requite your next paycheck to the nearest mechanic. Problems that trigger a bank check engine low-cal are sometimes bones and quick to set. Don't ignore it, either, and get it checked out as quickly equally possible.

Here are the 10 most common problems that can trigger a check engine calorie-free. Go on in mind that the mistake code that acquired the light to plow on in the first place is stored in your auto'south onboard computer, and y'all can retrieve it using a simple Bluetooth-powered device linked to an app to get a precise idea of what exactly is incorrect under the hood. Doing this on your own will salvage you money in the long run.

Oxygen sensor failure

The oxygen sensor (sometimes called an O2 sensor) measures the amount of unburnt oxygen in a car's exhaust system. Information technology sends data to the vehicle's calculator, which uses it to regulate the mixture of air and fuel that enters the cylinders. An engine will continue running even if an O2 sensor needs to be replaced, only information technology will fire more fuel than usual. In the long run, a bad O2 sensor tin impairment components like spark plugs and the catalytic converter. It may also cause a automobile to fail an emissions examination.

On average, a quality O2 sensor volition prepare you lot back about $175, but the cost of labor will vary greatly depending on the vehicle'southward make and model, every bit well every bit your geographical location. Finally, go along in mind that most late-model cars take more than than ane O2 sensor.

Loose fuel cap

A loose fuel cap is 1 of the about common reasons why the bank check engine light turns on. The cap is a crucial part of a car's fuel delivery organization. It notably prevents gasoline fumes from leaving the fuel tank, and information technology helps keep the whole organization under the right pressure level.

If your bank check engine lite turns on immediately after a make full-up, pull over and brand sure the cap isn't loose — or still on your motorcar'south roof. Sometimes the cap needs to exist replaced, but it's non a problem that's going to hit your wallet difficult. Near machine parts stores carry universal-fit gas caps that toll somewhere in the vicinity of $15.

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Catalytic converter failure

The catalytic converter is integrated into a vehicle's exhaust system. It turns the carbon monoxide generated during the combustion process into carbon dioxide. Information technology'due south a adequately simple office, and its failure can often be prevented. That's good news because a new one costs between $200 and $600 depending on the brand and model. Every late-model car that runs on gasoline has a catalytic converter.

Performing regular maintenance (such equally oil changes) on fourth dimension is key to keeping your automobile's catalytic converter in working order. If you live in the city and mostly drive short distances, accept your auto on the highway every now and then to ensure the catalytic converter doesn't become clogged. And as always, keep your eyes and ears open up for unusual sounds or discolored smoke coming from the exhaust.

Spark plug/ignition whorl issues

Put just, an ignition ringlet generates the electricity the spark plugs need to ignite the fuel and air mixture in the cylinders. Archetype cars have a unmarried whorl, but many modern vehicles use one roll per cylinder (information technology'due south oft called a roll pack). If your ride has a V8 nether the hood, y'all could have viii dissever coils. The monstrous Bugatti Chiron has xvi. No affair how many y'all have though, a malfunctioning coil will almost certainly trigger the check engine light, but remember, if your auto burns diesel fuel, you accept neither ignition coils nor spark plugs.

Speaking of spark plugs, worn or fouled plugs tin cause a multifariousness of issues including an engine misfire and hesitation under heavy acceleration. A worn ringlet can showroom the same symptoms, and it tin can cause the auto to shut off unexpectedly. A quality spark plug costs between $10 and $twenty, while a curl is mostly in the $l range. Irresolute your own spark plugs is also easier than it sounds.

Bad spark plug wires

Equally its name implies, a spark plug wire transfers electricity from the gyre to the spark plug. Without it, the fuel and air mixture in the cylinders wouldn't ignite. The vast majority of cars use a single wire per cylinder, but there are models — notably, some older Mercedes-Benzes — with two spark plugs per cylinder and, consequently, two wires. Proceed in heed that nigh newer cars do not use spark plug wires, however.

Symptoms of bad spark plug wires include a rough idle, a noticeable drop in engine performance, and lower gas mileage. Expect to spend almost $50 on a prepare of plug wires. Swapping them out is easy — it takes a few minutes and requires no special tools or cognition.

Mass airflow sensor failure

The mass airflow (MAF) sensor monitors how much air enters the engine. Information technology'south a part of the engine-management organisation, so your motorcar wouldn't be able to adjust to changes in altitude without it. Symptoms of an MAF failure include a rough idle, trouble starting, and a sudden change in the position of the throttle pedal. Reduced gas mileage and stalling can also point a MAF problem.

A MAF for a late-model car typically costs between $120 and $150.

Issues with an aftermarket alert

An aftermarket alarm organization can wreak havoc on your motorcar if information technology'southward not installed properly. Information technology can bleed the battery, trigger the check engine calorie-free, or even prevent the vehicle from starting. Then, when you least expect it, it'll go off in the heart of the night considering a leaf from an oak tree barbarous on the hood.

If the above issues audio familiar, y'all'll need to take the alarm fixed, reinstalled, or replaced entirely by a competent mechanic. Getting it done right in the start place might cost a niggling bit more than, only the peace of mind that comes with having a fully functional alarm is priceless.

Vacuum leak

Every automobile has a vacuum arrangement that performs a broad variety of functions. The brake booster is vacuum-operated, and the vacuum system also helps lower emissions by routing the fumes as gasoline evaporates through the engine. If your car'southward idle begins to surge or settles at an unusually high rpm, a vacuum leak could be the culprit.

Vacuum hoses can dry out and crack as they historic period, especially if they're exposed to intense oestrus or farthermost cold. This is the most common cause of vacuum leaks. Other common issues include cracked fittings and loose connections. Vacuum lines cost but a few bucks each, just tracing the source of the leak can exist time-consuming — and expensive if y'all're not performing the work yourself.

Exhaust gas recirculation valve failure

The exhaust gas recirculation (EGR) organisation lowers the corporeality of nitrogen oxide that comes out of the motorcar's engine and helps it run more than efficiently. It directs the hot exhaust gases back into the combustion chambers, which makes fuel easier to burn. It also reduces emissions.

The EGR valve tin can get clogged or fail entirely. If you lot're even slightly mechanically inclined, you can remove the valve, clean it, and reinstall information technology in a relatively short amount of fourth dimension. If the valve needs to be replaced, await to pay at to the lowest degree $125 for a brand-new, OEM-quality unit.

Expressionless battery

The bombardment is equally elementary as it is important; without it, your car won't start. Today's batteries last much longer than before and they're maintenance-gratuitous. The price of a new i depends on the blazon of automobile you lot drive, but programme on spending at least $100 for a quality battery.

Changing or charging a bombardment on your own is a relatively like shooting fish in a barrel task, but continue in mind that in some belatedly-model cars, information technology'southward cached under countless plastic covers, and it might be a trivial difficult to access. Also, note that disconnecting the battery will ofttimes reset your stereo system. If yous don't have the lawmaking, ask your local dealer for it before you unbolt the positive and negative terminals. Otherwise, yous'll be driving in silence.

My cheque engine light is on. Now what?

Modernistic cars are brimming with high-tech bells and whistles, simply you inexplicably still need a separate, aftermarket device to decipher why the check engine light is on. Most motorists only take their car to the dealership. That's the easy manner out, but it'due south also the well-nigh expensive road to take. If you want to skip a trip to the repair store, spend a few dollars on a Bluetooth-compatible OBD 2 scanner (or a more than advanced adapter) and download a uniform app similar Torque from either the Google Play Store or Apple'southward App Store. You can get the tool and the app for less than $15, which isn't bad considering many shops charge between $50 and $100 to pull codes from the ECU.

Ready? Start by finding your motorcar'south OBD II port. It's usually in the driver's footwell, not far from the hood release, only sometimes it'south subconscious backside the middle console or in a compartment built into the floor. Plug in the scanner, launch the app on your phone, and the error codes stored in the car's ECU volition appear on the screen. Sometimes the codes are clearly explained; other times, you lot'll demand to do a scrap of searching to figure out what something like P1301 means. Repair manuals are useful for deciphering codes, merely Google usually has the answer.

Fault codes are a useful diagnostic tool that can help you lot figure out where to start when your car needs a repair; but be careful to empathize their limitations. Error codes don't e'er tell the total story.

Once, when working on a relative's car that had lost all power, the ECU codes indicated a problem with the turbo. Just the event wasn't with the role itself — it was a croaky vacuum hose. Long story short: Having a list of codes at your disposal doesn't always hateful a straightforward solution. You may need to spend a few minutes (or, at worst, a couple of hours) poking around the engine bay to find the issue.

At that place are professional-grade code scanners that are more precise but likewise much more than expensive. The scanner can merely give you a code; you lot also need in-depth noesis of what each code means or a useful way to find out. Alternatively, some auto parts stores volition run a diagnostic test for free. However, getting a Bluetooth scanner and an app will salvage you fourth dimension and money while making you more car-savvy. Brand certain the unit you pick is compatible with your car before ownership it. Some cheaper scanners won't work with every brand and model, and so information technology pays to do your enquiry.

Will the check engine light tell me when I should gear up my car?

The check engine light provides an thought — sometimes precise, sometimes vague — of what's wrong with a car. Withal, it does not replace a skilled mechanic or routine maintenance.

In other words, don't await until the check engine light comes on to get your car maintenance done. The ECU will not warn you that the water pump is about to fail, that one of the ball joints is worn, or that the A/C will stop blowing cold air in mid-August. Many people call back that the check engine light serves the same purpose equally a check-up reminder when it really alerts y'all that you're probably due for a repair. By that signal, the impairment has already happened in many cases.

You can remember of machine maintenance as a ii-step process. The starting time and most critical is routine, preventative maintenance. You lot should do these tune-ups on a schedule and not in response to any bug. The 2nd is timely diagnostic maintenance which is responsive to changes like new sounds, smells, or feelings as yous drive.

You besides want to be familiar with your motorcar's basic needs, similar how often to change the oil and coolant or supersede brake pads. A lilliputian enquiry into your specific vehicle and basic mechanics tin salve you time and coin in the long run. If yous're consistent with a regular maintenance routine, you may never see that picayune orangish engine low-cal popular on at all.

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