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Buick Check Engine Light (Causes & Fixes)

Updated: Jan 9

The check engine light (CEL), along with other dashboard warning lights, will appear when you turn on the ignition in your Buick vehicle to make sure they're functioning properly. They should turn off shortly after. If your Buick check engine light doesn't go away, there could be an issue.

Minor problems like a loose fuel filler cap or an issue with the engine control unit (ECU) are often the cause of a check engine light.

The issue can usually be resolved by simply restarting your vehicle or using an OBD scanner to reset any error codes.

Common causes for the Buick check engine light to come on include faulty spark plugs, a malfunctioning oxygen sensor, mass air flow sensor (MAF) or catalytic converter.

However, numerous causes of a CEL exist and it could be anything, it could something minor or something quite serious.


Table of Contents:

orange check engine light illuminated on dashboard

Common Symptoms of a Buick Check Engine Light

There are some common symptoms you may notice if your Buick has the check engine light illuminated, such as those listed below.

  • Engine running rough

  • Reduced performance

  • Poor throttle response

  • Unusual noises and sounds

  • Stalling or cutting out

  • Overheating

  • Smoke from the exhaust

  • The vehicle goes into failsafe mode (limp mode)

The symptoms you may notice depend entirely on the cause of the check engine light, if its something minor such as a loose fuel cap you'll notice no symptoms other than the warning light.

If it's something more serious such as engine failure, you'll notice many symptoms.

To determine the cause of the problem you can use an OBD scanner to find out which diagnostic trouble codes have been generated. From there you can begin your investigation into the issue and figure out what's caused it.

Types of Check Engine Light

The check engine light on your Buick can be intermittently on, constantly on, or can also be blinking / flashing, each variation of the CEL has its own meanings.

  • Intermittent: If your check engine light comes on occasionally, pay attention to any changes in your vehicle's performance when the light is on. If you do notice a change, try driving it as little as possible until it can be repaired. Most likely, something is about to fail, and you risk your car not starting again, if the issue is intermittent it's typically a sensor failing or an electrical issue.

  • Constantly on: The onboard diagnostic system in your car has found a problem that's serious enough to trigger the check engine light. Even if your car may seem to be running well, it's advisable to take it in for repair work as soon as possible to avoid developing more problems. Avoid driving or starting the vehicle if you can.

  • Blinking: If your Buicks check engine light is flashing or blinking, it usually means your car has a serious problem and you should pull over when it's safe to do so. Its usually best to have the vehicle towed or recovered and have it fixed. You should avoid driving or starting the vehicle.

Failsafe Mode (Limp Mode)

If you notice a consistent drop in performance when the check engine light is illuminated, your Buick may have entered failsafe mode (also called "limp mode") to avoid further damage.

In the case of failsafe mode being triggered, you should avoid starting or driving your vehicle until the issue is resolved.

Common Causes of a Check Engine Light for Buick Vehicles

Because Buick is owned by GMC, they can have similar causes of the engine light. There can be many causes of a check engine light, some common causes associated with a Buick vehicle include the following.

  • Loose fuel cap

  • Faulty catalytic converter

  • Faulty spark plugs or wiring

  • Faulty oxygen sensor

  • Faulty MAF sensor

Loose Fuel Cap

A loose, damaged, or missing fuel filler cap can lower fuel pressure and allow fuel vapour to escape, reducing fuel efficiency and releasing harmful emissions. This can be detected by the ECU, causing the check engine light to illuminate.

a fuel cap on a vehicle left partially open

Faulty Catalytic Converter

Material may block your catalytic converter over time, particularly in higher mileage vehicles. The catalytic converter is an essential component of the emissions system, since it removes dangerous emissions.

A faulty or blocked catalytic converter may have a significant influence on fuel efficiency and vehicle performance. The ECU uses several sensors within the exhaust that can trigger the CEL.

a person removing a catalytic converter from the underneath of a vehicle

Faulty Spark Plugs or Wiring

Spark plugs are a replaceable part and must be replaced about every 30,000 miles. Your spark plugs produce a hot spark, which ignites the air-and-fuel mixture in the cylinder and allows your engine to start and run.

Sometimes the wiring for the spark plugs in your Buick can also cause issues if they are damaged, corroded, loose, or need replacing.

Faulty spark plugs or spark plug wires may cause your engine to misfire, lowering fuel efficiency, performance, and even preventing it from running entirely. This can cause the check engine light to come on.

a hand holding a spark plug

Faulty Oxygen Sensor

The oxygen sensor may need to be replaced as a result of prolonged exposure to exhaust gas.

The oxygen sensor provides information about the air-fuel mixture to the ECU. A defective oxygen sensor can cause the ECU to produce an incorrect air/fuel ratio.

An engine with insufficient fuel can result in engine failure, whereas an engine with much fuel produces excessive smoke and emissions.

Faulty MAF Sensor

The mass air flow (MAF) sensor can malfunction when exposed to dirty air. The MAF sensor detects the quantity of air entering the engine and aids in the appropriate air-fuel mixture.

A defective MAF sensor may cause your engine to misfire, resulting in poor fuel efficiency, performance, and even more engine damage.

a person pulling the mass air flow sensor from an intake pipe in a car

Possible Solutions

Its always advised to avoid driving or starting a vehicle without first knowing the cause of a check engine light. You should use an OBD reader compatible with Buick to figure out the cause of the warning light.

First try to service your Buick vehicle at a GMC servicing garage, this may fix any issues with dirty oil, low oil levels, and other possible causes of the engine light associated with servicing.

If you are not noticing any drivability issues, any vibrations, misfiring or anything serious you could try the following steps to see if they resolve the issue.

  • Make sure your Buicks fuel filler cap is tight and in place correctly.

  • Open the engine compartment and check for any evident damage, loose parts, damaged electrical components, etc.

  • Visually check the battery connections' are securely attached.

  • 15 minutes after turning off the car, restart it and look for the check engine light.

If no issues were found by inspecting the vehicle and the check engine light still came on, you could try the following steps.

  • Clear any fault codes with a reputable OBD scanner.

  • Turn off the vehicle and disconnect the negative (ground) connector from the battery.

  • The mass air flow sensor should be taken out and cleaned using an electrical cleaner, such as a compressed air duster or contact cleaner.

  • Look for damage or loose connections at any obvious electrical connections.

  • Put everything back where it came from and reconnect the battery's negative (ground) connector after 15-30 minutes (to allow the ECU to reset).

  • Check for a check engine light after starting the vehicle; if it does not come on, test drive your Buick for 15 to 30 minutes.

If the check engine light is still appearing, use an OBD scanner to finds fault codes and further investigate those. You should avoid driving and starting the engine if any issues are noticed.

Will Your Buick Check Engine Light Go Away On Its Own?

If the check engine light (CEL) on your Buick vehicle is illuminated, it is generally not recommended to simply wait and hope that it will turn off on its own.

While it is possible that the engine light may turn off on its own if it was triggered by a minor issue, such as a loose fuel filler cap, this is not always the case. In many instances, the warning light is illuminated due to a more serious issue that requires attention and repair.

If the check engine light on your Buick is illuminated, it is important to take action to diagnose and fix the underlying issue as soon as possible.


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