top of page

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.