Why does my check engine light come on sometimes?

Reason #1 – A Loose or Faulty Gas Cap – Yes, surprisingly this can cause the Check Engine or Service Engine Soon light to come on. Start by taking the gas cap off and putting it back on. You’ll then need to drive the vehicle a few times to get the Onboard Diagnostic (OBD) system to reset and turn the light off.

Why is my check engine light on but everything is fine?

These problems can range from faults within the electrical system, the engine, fluid levels or to problems within the car’s emissions system. The problem can even be as simple as forgetting to tighten your gas cap – in fact, this is the most common reason why check engine lights appear in the first place.

Why is my Subaru check engine light on?

If the check engine light in your Subaru Legacy starts twinkling, that means that the problem needs rapid attention and your Subaru should be delivered in suddenly. This blinking light usually indicates a severe engine misfire allowing unburned fuel to be dumped into the exhaust system. …

Can a check engine light come on for no reason?

The check engine light can come on for many reasons. For example, something as simple as a loose gas cap can trigger the warning. And major problems, such as failed internal engine components, can turn on the light, as well.

Will check engine light go off after tightening gas cap?

The check engine light should go off after you drive for several minutes if the light was caused by a loose gas cap. Pay attention to the dashboard after the check engine light experience. If you find that the light keeps coming on, and goes off again once you tighten the gas cap, then your gas cap is too loose.

What is the most common reason for a check engine light?

Replacing a faulty oxygen sensor — a sensor used to optimize a vehicle’s fuel-to-air mixture to increase gas mileage and reduce emissions — is the most common cause for a check engine light. With over 400,000 repairs nationwide, oxygen sensor replacements account for 8% of all check engine light repairs.

How long can you drive with check engine light on?

When the check engine light is solid, you can typically drive the car for hundreds of miles without an issue. Of course, that depends on which code is stored in the vehicle’s computer. If an engine sensor is faulty, the car will usually use made up sensor values to keep running.

Will a dirty air filter cause a check engine light?

A dirty air filter is one of the things that can cause your Check Engine light to come on, caused by an inadequate supply of air to the engine that results in a buildup of carbon deposits. Have your mechanic scan your vehicle to track down the source of the problem, as it could be as simple as replacing the air filter.

How long does it take for the check engine light to go off after replacing gas cap?

So first things first, pull over (as soon as it’s safe) and make sure your gas cap is on tight. If this was indeed the trigger, your check engine light should go off within 10 or 20 miles once you’re back on the road.

What happens when a Subaru check engine light fails?

If one of these sensors fails, it will trigger a fault code. The code is then stored in the computer until a diagnostic scan is run on the ECU to diagnose the problem.

How do you reset check engine light on Subaru Outback?

Wait 5 minutes, then reconnect the cable and tighten the retaining nut. Start the engine and wait for the Subaru’s computer to reset the check engine light.