2021 GMC Sierra 3.0 Diesel Check Engine Light

When you are driving the 2021 GMC Sierra 3.0 Diesel and suddenly the check engine light is on, It is a very frustrating experience. The first thing you can do is ease your mind and then find the cause of the check engine light. If you don’t know about the causes which illuminate the check engine light, you don’t need to panic.

In this blog, we are going to explain the detailed reasons that triggered the check engine light in a 2021 GMC Sierra 3.0 Diesel and will offer tips and tricks on how to solve the issue.

Possible causes for the check engine light to come on in the GMC Sierra 3.0 diesel

The check engine light in your GMC Sierra 3.0 diesel can come on for a variety of reasons, ranging from minor issues to more serious problems that require immediate attention. Here are some possible causes:

1. Exhaust gas recirculation (EGR) valve failure

The EGR valve recirculates exhaust gas back into the engine to help reduce emissions. If the EGR valve fails, it can cause the Check Engine Light to come on and reduce fuel efficiency.

 Symptoms of EGR valve failure can include:

• Reduced fuel efficiency
• Increased emissions
• Rough idle
• Engine hesitation
• Black smoke from the exhaust

Solutions:

• Clean the EGR valve.
• Replace the EGR valve.

2. Diesel particulate filter (DPF) failure

The DPF traps soot and other pollutants from the exhaust gas. If the DPF becomes clogged, it can cause the Check Engine Light to come on and reduce engine power.

Symptoms of DPF failure can include:

• Reduced engine power
• Increased emissions
• Black smoke from the exhaust
• Difficulty starting the engine

Solutions:

• Clean the DPF.
• Replace the DPF.

3. Turbocharger failure

The turbocharger boosts engine power by compressing the intake air. If the turbocharger fails, it can cause the Check Engine Light to come on and reduce engine power.

Symptoms of turbocharger failure can include:

• Reduced engine power
• Increased emissions
• Black smoke from the exhaust
• Whining or whistling noise from the engine compartment
• Oil leak from the turbocharger

Solutions:

• Repair the turbocharger.
• Replace the turbocharger.

4. Fuel injector failure

The fuel injectors deliver fuel to the engine cylinders. If a fuel injector fails, it can cause the engine to misfire and reduce fuel efficiency.

Symptoms of fuel injector failure can include:

• Engine misfire
• Reduced fuel efficiency
• Increased emissions
• Rough idle
• Black smoke from the exhaust

Solutions:

• Clean the fuel injectors.
• Replace the fuel injectors.

5. Mass airflow sensor (MAF) failure

The MAF sensor measures the amount of air entering the engine. If the MAF sensor fails, it can cause the engine to run rich or lean, which can reduce fuel efficiency and cause the Check Engine Light to come on.

Symptoms of MAF sensor failure can include:

• Reduced fuel efficiency
• Increased emissions
• Rough idle
• Engine hesitation
• Black smoke from the exhaust

Solutions:

• Clean the MAF sensor.
• Replace the MAF sensor.

6. Oxygen sensor failure

The oxygen sensors measure the amount of oxygen in the exhaust gas. If an oxygen sensor fails, it can cause the engine to run rich or lean, which can reduce fuel efficiency and cause the Check Engine Light to come on. Symptoms of oxygen sensor failure can include:

• Reduced fuel efficiency
• Increased emissions
• Rough idle
• Engine hesitation
• Black smoke from the exhaust

Solutions:

• Clean the oxygen sensors.
• Replace the oxygen sensors.

7. Intake manifold runner control (IMRC) valve failure

The IMRC valves control the flow of air into the intake manifold. If an IMRC valve fails, it can cause the engine to run rough and reduce fuel efficiency.

Symptoms of IMRC valve failure can include:

• Rough idle
• Reduced fuel efficiency
• Engine hesitation
• Black smoke from the exhaust

Solutions:

• Clean the IMRC valves.
• Replace the IMRC valves.

8. Exhaust gas temperature (EGT) sensor failure

The EGT sensor measures the temperature of the exhaust gas. If the EGT sensor fails, it can cause the engine to run too hot, which can damage the engine and cause the Check Engine Light to come on.

Symptoms of EGT sensor failure can include:

• Overheating engine
• Reduced engine power
• Increased emissions
• Black smoke from the exhaust

Solutions:

• Clean the EGT sensor.
• Replace the EGT sensor.

Here are some additional tips for troubleshooting a Check Engine Light in a 2021 GMC Sierra 3.0 Diesel:

• Check the fuel cap to make sure it is tight. A loose fuel cap can cause the Check Engine Light to come on.
• Check the fuel filter. A clogged fuel filter can reduce fuel flow and cause the Check Engine Light to come on.
• Check the oil level and condition. Low oil or dirty oil can cause the Check Engine Light to come on.
• Have the vehicle scanned for diagnostic trouble codes (DTCs). DTCs can help a mechanic to diagnose the problem and make the necessary repairs.

If you are not comfortable troubleshooting the Check Engine Light yourself, it is best to take the vehicle to a qualified mechanic.

1: How to Reset the Check Engine Light on a 2021 GMC Sierra 3.0 Diesel?

There are two ways to reset the check engine light on a 2021 GMC Sierra 3.0 Diesel:

1. Using a scan tool

1. Connect the scan tool to the OBD-II port on the vehicle.
2. Select the “Reset Check Engine Light” option on the scan tool.
3. Follow the on-screen instructions to reset the light.

2. Disconnecting the negative battery cable

1. Turn off the vehicle and open the hood.
2. Locate the negative battery cable.
3. Loosen the nut that secures the negative battery cable to the battery terminal.
4. Remove the negative battery cable from the battery terminal.
5. Wait 30 seconds.
6. Reconnect the negative battery cable to the battery terminal and tighten the nut.
7. Close the hood and start the vehicle.

The check engine light should now be reset.

Additional tips:

• Before you reset the check engine light, it is a good idea to have the vehicle scanned for diagnostic trouble codes (DTCs). DTCs can help a mechanic diagnose the problem that caused the check engine light to come on.
• If you are not comfortable resetting the check engine light yourself, it is best to take the vehicle to a qualified mechanic.

Also Recommended: Can Cold Weather Cause the Check Engine Light to Come On?

2: Conclusion

If the Check Engine Light comes on in your 2021 GMC Sierra 3.0 Diesel, there are a number of possible causes, ranging from minor issues to more serious problems that require immediate attention. Some of the most common causes include:

• EGR valve failure
• PDF failure
• Turbocharger failure
• Fuel injector failure
• MAF sensor failure
• Oxygen sensor failure
• IMRC valve failure
• EGT sensor failure

If you are not comfortable troubleshooting the Check Engine Light yourself, it is best to take the vehicle to a qualified mechanic. They will be able to scan the vehicle for diagnostic trouble codes (DTCs) and identify the cause of the problem. Once the problem has been identified, the mechanic can make the necessary repairs to get your vehicle back on the road.

To help prevent the Check Engine Light from coming on in the first place, it is important to follow the manufacturer’s recommended maintenance schedule. This includes changing the oil and fuel filter regularly and having the vehicle inspected by a qualified mechanic on a regular basis.