Q: Check engine light

asked by on January 05, 2018

Check engine light came went too two different mechanics both said they don’t see anything faulty one of them said it could be small leak somewhere usually gas cap but doesn’t seem that could be it other said maybe changing sensor which was changed the o2 went off now came back on 4 days later not sure what else I can do car is not running different

My car has 51000 miles.
My car has an automatic transmission.

The cause of the issue would depend on which trouble codes are stored in your vehicle. If you have a small evap leak on your vehicle I would recommend having the vacuum lines check to determine if any small cracks like that might enable a small vacuum leak to cause a check engine light.

Generally, the check engine light comes on when something fairly serious is going on with the vehicle. This can happen for many different reasons such as a faulty mass air flow sensor, a faulty O2 sensor, a bad catalytic converter, bad spark plugs or spark plug wires and many other reasons. Due to the wide range of possibilities for the check engine light to come on, the best and most efficient way to narrow down the scope of what may be causing this is to have the vehicle hooked up to a scanning tool to download any potential fault codes that may have registered in the computer. This will allow a mechanic to determine more specifically what to look for in diagnosing your vehicle. I would recommend having an expert from YourMechanic come to your location to take a look at your vehicle to determine what may be causing your check engine light to come on.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $70/hr

What others are asking

How do I use the Uconnect system to make a phone call?
The Uconnect system is a Bluetooth-connected system that allows you to use your cell phone through your vehicle’s audio system. It is a hands-free, voice-operated system that lets you safely operate your cell phone while driving. Making a phone call...
Car shakes and won't accelerate.
This may be due to an issue with your ignition system. A severe misfire can cause an engine to accelerate very poorly and can also cause the vehicle to shake badly. If you have a check engine light I would...
How do I turn on panic mode?
To turn on panic mode, press the panic button on the remote transmitter. When panic mode is turned on, the horn will honk and the lights will flash for roughly 30 seconds. To turn off panic mode, press any button...
What does the Intelligent Key battery discharge Warning Light mean?
The Intelligent Key battery discharge Warning Light is located on the instrument panel. This light illuminates when the batter in the Intelligent Key is running low. Replace the battery as soon as possible, to avoid it dying during use.
Vehicle makes rattling noise when idling
Based upon the information provided, an inspection of the drive belt and air conditioning system should be performed. The squealing noise indicates your drive belt is under strain. If the belt breaks, you will not be able to drive your...
Replaced only 1 tire in AWD vehicle.
It is recommended on any vehicle with AWD (all-wheel-drive) to replace all four tires (https://www.yourmechanic.com/article/how-to-know-when-to-replace-tires_2) at the same time. The reason behind this need is due to the computer on the vehicle constantly monitoring the speed of each wheel. The...
Front end, drivers side, loud banging and knocking.
You may have a bad strut or strut bushings or some other worn out front end part. I would recommend having a mechanic inspect the complete front end (https://www.yourmechanic.com/services/brakes-steering-and-suspension-system-inspection) to isolate any problems you may have. I have seen struts...
Check Engine Diagnosis - Transmission controller Communication error codes
Hello there, many different faults can cause this combination of codes on your 2006 Chrysler PT Cruiser. When we see loss of communication codes with Transmission Control Module (TCM) internal faults, this usually means one of the following: the TCM...
Magnet stuck on spark plug.
I do not have a vehicle listed so I am not sure how to guide you. but depending on the location of the spark plug hole, he may be able to use needle nose pliers to go into the hole...

Related articles

The Most Common Error Codes for Transmission Problems
If your Check Engine Light has come on, there are a number of conditions that could be causing it. Many are related...
Symptoms of a Bad or Failing EGR Temperature Sensor
Common signs include engine ping or knock, the Check Engine Light coming on, and failing an emissions test.
How to Replace an Air Fuel Ratio Sensor
The air fuel ratio sensor fails within a vehicle if the check engine light comes on. Poor engine performance results from oxygen sensor failure.