An illuminated Check Engine Light (CEL) on your Chevrolet’s dashboard can leave you feeling anxious.
You may wonder: What could have possibly activated it?
So, let’s explore the various triggers of a Chevrolet Check Engine Light and what you can do to resolve it.
This Article Contains:
- 8 Key Reasons behind the Chevrolet Check Engine Light
- What Should You Do if the Chevrolet Check Engine Light Appears?
- How to Reset the Chevrolet Check Engine Light
- How Much Does a Chevrolet Check Engine Light Diagnostic Test Cost?
8 Key Reasons behind the Chevrolet Check Engine Light
The Check Engine Light on a Chevrolet and other General Motors (GM) vehicles is an amber or yellow light shaped like an engine outline.
What does the Check Engine Light mean?
It indicates something’s wrong with the engine or emissions control system. Your car’s Engine Control Unit (ECU) will also store a Check Engine Light code once it detects the problem.
However, there can be various reasons for an illuminated Chevrolet Check Engine Light, such as worn spark plugs or vacuum leaks. Let’s review them.
1. Loose Gas Cap
A loose gas cap allows fuel vapors in the gas tank to escape into the atmosphere. The EVAP sensor in the fuel tank can detect this leak, following which the ECU stores a trouble code and turns on the Check Engine Light.
Though a loose gas cap may not seem as menacing as an engine problem, it can let contaminants into the fuel system and damage the fuel injectors.
2. Bad Spark Plugs
Spark plugs fouled with engine oil, coolant, or carbon won’t deliver the required spark for igniting the air-fuel mixture. This can cause engine misfires, resulting in a related trouble code and active Check Engine Light.
3. Damaged Spark Plug Wires
Spark plug wires on older cars and work trucks carry high voltage current from the distributor to the spark plugs. Damaged spark plug wires can cause ignition problems, leading to engine misfires and an illuminated Check Engine Light.
4. Faulty Ignition Coil
A bad ignition coil won’t provide the high-voltage electric current to the spark plug for igniting the air-fuel mixture. This can again lead to engine misfires, the ECU registering a fault code and triggering the Check Engine Light (CEL).
5. Malfunctioning Oxygen Sensor (O2 Sensor)
Your Chevrolet’s exhaust system has an oxygen sensor before and after the catalytic converter. The upstream sensor checks the engine’s combustion efficiency, and the downstream one monitors the converter’s output. A faulty oxygen sensor on Chevrolet cars or work trucks like the Chevrolet Silverado may relay irrational readings to the ECU, activating the CEL and a related diagnostic trouble code.
6. Defective Mass Airflow Sensor (MAF Sensor)
The MAF sensor lets the ECU know how much air enters the engine to help it adjust fuel injection. A malfunctioning MAF sensor may trick the ECU into injecting an incorrect amount of fuel. This can produce either a lean or rich fuel condition, causing inefficient combustion. Consequently, a diagnostic trouble code gets stored, and the CEL appears.
7. Vacuum Leak
A damaged vacuum hose or intake manifold gasket allows unmetered air into the engine, disturbing the air-fuel ratio. It can result in a misfire or the engine running with reduced efficiency. Once the O2 sensor in the exhaust system detects this, it triggers an error code and an illuminated Check Engine Light.
8. Catalytic Converter Issues
Frequent engine misfires due to worn spark plugs or other causes can damage catalytic converters on both new vehicles and pre-owned vehicles. If the catalytic converter is damaged, the O2 sensor will detect this and alert the ECU, leading to a lit CEL and a related Check Engine Light code. A clogged catalytic converter can also impact normal combustion and trigger the Check Engine Light.
Note: Some aftermarket accessories can also bring on the CEL and register a Check Engine Light code by draining the battery. Use only genuine GM accessories to avoid such issues.
Returning to the drivability of a Chevrolet with an active CEL, let’s see how you should go about it.
What Should You Do if the Chevrolet Check Engine Light Appears?
The Check Engine Light can illuminate under different scenarios. Here are three different cases of this warning light being active:
A. Steady Check Engine Light
You can still drive your car if the Check Engine Light comes as a steady yellow light, but it’d be best to get your vehicle inspected by a mechanic soon. This will help prevent the existing emission or engine problem from causing further damage.
Check if the gas cap is fine and properly secured before heading to a Chevrolet service center.
If you have a defective gas cap, replace it with a new inventory to see if the illuminated Check Engine Light disappears. Bad gas caps can trigger the CEL even on new vehicles without other faults, let alone old or pre-owned vehicles.
B. Steady Check Engine Light with Other Warning Lights
Don’t drive if you have a steady Check Engine Light with other dashboard lights, such as the oil pressure light, coolant temperature light, brake warning light, etc. Your car may require an urgent oil change, brake service, or some other vital repair. Get roadside assistance or have your car towed to a workshop for inspection.
C. Flashing Check Engine Light
A flashing Check Engine Light on your Chevrolet Silverado or any other General Motors model requires immediate attention. You absolutely shouldn’t drive if the CEL blinks. Instead, get your vehicle towed to a service center. The CEL generally flashes due to frequent engine misfires that can overheat the catalytic converter and damage it.
After your mechanic addresses the issues that triggered the Chevrolet Check Engine Light, they’ll reset it before handing over the vehicle to you.
How to Reset the Chevrolet Check Engine Light
Here’s how a mechanic will do it:
A. Using an OBD-II Scanner
- Locate the OBD port.
- With the engine turned off, connect the OBD II scanner to the port.
- Turn the ignition key to the “on” position.
- Press the “erase” or “clear” button on the OBD II scanner to reset the Check Engine Light.
- Turn the ignition key back to the “off” position.
- Disconnect the scanner.
- Start the engine to see if the Check Engine Light has disappeared.
B. Disconnecting the Battery
Your mechanic may use this method if you own an older Chevrolet without an OBD-II system.
- Turn off the engine and open the hood.
- Locate the negative battery terminal and disconnect it.
- Reconnect the negative cable after about 15 minutes.
- Start the car to see if the Check Engine Light has gone away.
The service center technicians will conduct a Check Engine Light diagnosis to determine the cause of the CEL. Let’s see how much you’ll have to shell out for this.
How Much Does a Chevrolet Check Engine Light Diagnostic Test Cost?
A Chevrolet Check Engine Light diagnosis may cost between $88-$209. This cost can depend on your vehicle’s model and manufacturing year, plus the labor charges at the Chevrolet service center.
The Chevrolet Check Engine Light alerts you about issues with your car’s engine or emissions control system. Have it addressed promptly to avoid poor fuel economy and engine damage.
Where to get the Chevrolet service done?
Look no further than AutoNation Mobile Service — a mobile auto repair service that can fix your car’s Check Engine Light and other problems right in your driveway.
Contact us to book your service hours and have our experienced technicians assist you, whether for a lit CEL, an oil change, or any other automotive troubles.