Check Engine Light is on

The check engine light of my truck was on I took it to autozone and they told me it was the termostat I changed it and the light of check engine turned off but only for two days also the temperature of the truck when up more than have way what could it be

My car has 118300 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
This can be caused by a number of things such as low coolant levels, a faulty thermostat, a clogged radiator or a failing coolant fan switch. As you may know the coolant fan switch helps to maintain the proper coolant temperature by turning on and off at specific temperature thresholds. When this switch is not working properly, this can cause the fans to come on intermittently, all the time or sometimes not at all. When this happens you will notice a temperature spike and drop occasionally as the fan comes on and off.

When your thermostat is not working properly or is stuck closed, this will not allow the coolant to properly circulate through the engine, which may cause the engine temperature to fluctuate erratically or in some cases just remain hot. You may also have a water pump that is beginning to fail. Water pumps often times will begin to produce a bit of a whining sound when they are starting to fail. A common problem also associated with this is the water pump may begin to leak around the water pump shaft due to the seal being damaged. In addition to leaking around the pump, you may have a leak elsewhere in the cooling system coming from one of the hoses going to or from the radiator. Lastly, you may have a failing cylinder head gasket allowing coolant to leak from the water passages into the cylinders resulting in the coolant being burnt in the combustion chamber with the fuel. If this is the case, you may also notice a bit of white smoke coming from your exhaust which is a product of the coolant being turned into a steam like vapor. I would suggest having an expert from Your Mechanic come to your home to diagnose your cooling system.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

If the check engine light in your GMC Canyon starts flashing, that means that the problem needs attention rapidly and your GMC should be brought in rapidly. A flashing light indicates that the problem is remarkably serious and if not taken care of rapidly may result in major and meaningful damage to the vehicle.
A loose gas cap is one of the most common reasons for the check engine light to go on. Check that your gas cap is screwed on securely and that it`s in good condition. If you have a tank of bad gas in the car, your check engine light may come on.
Reset A Check Engine Light: Two Techniques

Start the car, let it run for one second, and then turn it off. Let the engine sit quietly for two to three seconds, and then repeat the whole process two more times.

You can judge how serious an issue is by looking at the warning light. The check engine light can show up in two ways: Solid yellow/amber light: Indicates a less urgent issue. Flashing light or red: Indicates a severe problem that needs immediate attention.
If the check engine light illuminates, it will either blink or remain constantly illuminated, depending on the problem. A blinking light, or in some cars a red light instead of a yellow or orange light, indicates a problem that needs immediate attention. Either way, you should have the vehicle checked by a mechanic.
A check-engine light will shut itself off if the condition that caused it is remedied. So, if your converter is marginal, and you did a lot of stop-and-go driving, which creates high demand for the converter, that might have turned on the check-engine light.
Check your gas cap first. Many vehicles have a loose gas cap indicator that will be triggered before your check engine light comes on. If your gas cap is loose or the seal is not tight, the vapor leakage can cause your fuel system to trigger the check engine light.
Press the odometer`s Trip and Reset buttons while turning the ignition key ON. After turning the key ON, release the odometer Reset and Trip buttons to check if the Diagnostic Trouble Code or DTC appears on the odometer display.
The check engine light is constantly on: Your vehicle`s onboard diagnostic system has determined something is wrong and needs to be fixed. Although your vehicle may seem to be operating fine, it`s best to bring it in for service as soon as possible to prevent additional issues.
Check engine light flashing when the key is On position is usually a “bulb test” to confirm that the check engine light bulb is functioning whenever you turn on the ignition. The light should go off a few seconds after the engine starts running.
2021 Chevrolet Colorado Check Engine Light Flashing

Different amiable reasons for a Check Engine Light are faulty emissions control part, a malfunction with the fuel injection system, dirty mass airflow sensor, damaged oxygen sensor, faulty head gasket, or defective spark plugs to name a few.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Check engine light refuses to go off after engine replaced
ANSWER : Hello there, you have a long series of issues going on with your 2013 Hyundai Sonata. If you keep getting a repeating oil light on than there is likely a fault in that system.

Since this fault has lasted after the engine was replaced it could be a oil pressure sensor, wiring harness fault, ECU fault, oil pump, oil strainer clogged, or low oil pressure.

To diagnose this issue properly you need a complete vehicle inspection to start from square one and identify the root cause of all this.

Read Full Q/A … : Check Engine Light is on

While driving on freeway truck goes into a limp mode, and the check engine light, abs light, parking break light, service brake
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2006 Ford Mustang has check engine light on
ANSWER : There are countless potential causes for your illuminated check engine light. The mechanic manually turned off the light, but it came back on because the problem has not been fixed. The first place to start is retrieval of the stored diagnostic trouble codes (DTCs). These codes serve as a starting point for any further diagnostics a mechanic may perform. Codes will be stored anytime the check engine light is on. Since the first mechanic was unable to fix your concern, I recommend giving the professionals at YourMechanic a call. We offer expert check engine light diagnosis and repair.

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Car started to slow down and then the check engine light, battery, and engine oil light came on. What could cause this?
ANSWER : Hi there. It is possible that the battery cable came loose or the wires to the oil pressure sensor has came loose or failed. Check the battery cables and make sure that the terminals are tight and clean. Check the wires to the oil pressure sensor and make sure that they are connected and not broken. If everything looks good, then the oil pressure sensor may have failed. Plus, check the computer for codes and see what is stored. This will lead you to the part that could have failed. I recommend replacing the oil pressure sensor then checking to see if the lights will go out. If you need further assistance troubleshooting your vehicle, then seek out a technician, such as one from Your Mechanic, that can assist you with the warning lights that came on.

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Traction light/reduced engine power and check engine light coming on
ANSWER : Hello. From what you describe, it would appear that your vehicle may be experiencing some sort of intermittent wiring or sensor issue. If the problem occurred again after driving over a bump, then it may be possible that a damaged or loose wire is shorting or having contact issues. A common issue that can cause stalling is a faulty crank position sensor or wiring. I would carefully examine the engine for any loose or damaged wires. If the Check Engine Light comes back on, I would recommend having the trouble codes scanned before resetting the computer.

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Check Engine Light comes on after starting pickup
ANSWER : Hello there, thank you for asking about your 1992 Isuzu Pickup. A professional will have the correct equipment to read OBD1 codes. Retrieving the diagnostic trouble code(s) is the first place to start when diagnosing your vehicle. Increasing RPMs changes engine load, which can in turn affect many different sensors and components, causing the Check Engine Light to illuminate. The only way to narrow down the options and find the culprit is through in person diagnosis with an OEM compatible scan tool. A certified technician from YourMechanic can retrieve the OBD codes at your home or office.

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p0011 code,check engine light one, changed bank 1 vvt solenoid and check engine light still on?
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Car goes into limp mode when the check engine light and VSA light comes on
ANSWER : The lights that you have on and the vehicle going into fail safe mode is an indication you have a major system failure that will require computer to be tested for codes first. There are many possible codes it can be so the additional testing will be needed to isolate the cause of the problem.

Read Full Q/A … : Check Engine Light is on