Troubleshooting Buick Check Engine Light

Buick check engine light comes on when the On-Board Diagnostic (OBD) system detects a problem with the engine, transmission, or Evaporative Emission Control (EVAP) System.

Buick check engine light may be referred to as CEL, Malfunction Indication Lamp, MIL, Service Engine Soon, or SES light.

Check engine light may come on due to something as simple as a loose or defective gas cap. It can also indicate a more serious engine problem, transmission issue, or EVAP leak.

The check engine light itself does not provide much information on what is wrong with the vehicle. In this guide, you will learn how to read the fault codes yourself using an OBD-II scanner.

Symptoms

Common symptoms you may notice:

• Engine runs rough or won't stary running.
• Check engine light always on or flashing.
• Engine overheating
• Lack of power
• Poor throttle response
• Engine noise
• Smoke from the exhaust
• The vehicle won't shift gears, stuck in limp mode.

You may not notice any performance symptoms at all if your Buick check engine light is on due to an EVAP leak.

Common problems that trigger Buick check engine light to come on?

Common problems that trigger check engine light to come on:

• Worn spark plugs
• Bad oxygen sensor
• Faulty MAF sensor
• Defective Ignition coil
• Clogged catalytic converter
• EVAP Leak
• Loose Gas cap

There are hundreds of possible issues that can trigger the Buick check engine light to come on. To find out why your Buick to check engine light is on, read the fault codes with an OBD-II scanner.

• MAF Sensor - Mass airflow (MAF) sensors can get fouled by dirt over time, especially if performance filters are used. A dirty MAF sensor will give false readings, resulting in incorrect air-fuel mixture and engine running issues.  In most cases, dirt buildups can be easily cleaned off with a MAF cleaner fluid. Another possibility is a loose connector. Related Code: P0102

• Various vacuum leaks can cause engine running issues, especially noticeable on idle or low engine speeds. Tracking down leaks can sometimes be difficult, and you may need to use a smoke generating machine. Related Code: P0171 - system too lean 

• Catalytic Converter - Any higher-mileage Buick will most likely have some emission control issues triggering a check engine light.  In most cases, it is either caused by a clogged catalytic converter or a faulty downstream O2 sensor. Related Codes: P0410 and P0420

• Variable Valve Timing Issue - Problems with Variable Valve Timings are quite common on a 3.6L V6 engine. Besides, to check the engine light, you will experience a lack of acceleration, stalling, and poor throttle response. In most cases, the problem is within the timing chain, which needs to be replaced without delay. Related Code: P0008

• EGR Valve - EGR related problem is, in most cases, caused by a carbon buildup within an EGR valve. While this will not affect the engine performance in general, you might have a bit higher fuel consumption. If not too extreme, carbon buildup can be cleaned with EGR cleaner spray. Related Code: P0401

• Engine Coolant Temperature Sensor  - A bad coolant temperature sensor is a fairly common fault with some Buicks. It will give false temperature readings, causing rich engine operating conditions and incorrect temperature reading on your dashboard. In addition to the sensor itself, make sure the wiring is not damaged. Related Code: P0115

• Oxygen sensor - O2 sensors may fail, which then triggers the check engine light to stay on and fuel efficiency to decrease. O2 sensors monitor oxygen levels in the exhaust, which helps the engine control unit determine the fuel mixture. The engine control unit can determine if the fuel mixture is burning rich (less oxygen) or lean (more oxygen). 

How to Reset  Buick Check Engine Light

The following steps will help you learn how to diagnose and reset the Buick check engine light.

For this procedure, you will need an OBD-II scanner. If you don't have a scanner, you can purchase one online or stop by at your local auto parts store to have the codes read free of charge.

1. Park your Buick and turn off the ignition. Set the parking brakes.
2. Locate the OBD-II port under the dashboard and plugin your OBD-II scanner.
3. Turn on the ignition but do not start the engine.
4. Allow the scanner to turn on and communicate with the vehicle.
5. Read the codes by pressing Read Codes or Read Fault Codes on your OBD-II scanner, depending on the scanner. Reach each code to learn more about possible codes. To clear the check engine light, you need to fix the underlying problem before resetting the check engine light. 
6. Fix all issues found in step five. Come back to the main menu and select Clear Fault Codes, then OK. 

The instructions work in 1996 and newer vehicles such as Buick Enclave, Lesabre, Lacrosse, Verano, Regal, Lucerne, Rendezvous, Park Avenue, Allure, and Encore.

What does it mean when Buick Check Engine Light Flashing On and Off? 

One problem that must never be ignored is a check engine light flashing, especially if accompanied by engine shaking and juddering.

A check engine light going on and off intermittently signals an engine misfire, causing damage to the catalytic converter and other engine components.

It is not recommended to drive the vehicle if the check engine light is flashing.

Common problems that can cause Buick check engine light to flash on and off include old spark plugs, bad ignition coil, bad mass air flow sensor, or clogged catalytic converter. 

Conclusion

Buick check engine light or service engine soon light may come on for many reasons. 

The first step is to check the gas cap and tighten it. The check engine light may require a couple of days to reset on its own. An OBD-II scanner can be used if you would like to reset it as soon as you tighten the gas cap.

If the gas cap is not loose or damaged, the next step is to read the fault codes with an OBD-II scanner.

You can either take your car to the workshop for a full diagnosis or get your own scan tool. These devices come in all shapes, sizes, and prices to choose from.