What Causes the Check Engine Light on a Buick Century?

by Horacio Garcia
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A Buick Century can indicate one of several problems when the check engine light comes on. Some of the older Buick Century's have a yellow warning light and a red warning light for the check engine. The yellow light means the problem is minor, but if the red light comes on, the car should be stopped as soon as possible because there is something seriously wrong with the engine.

Wiring Harness

The check engine light can come on in a Buick Century if the wiring harness resting next to the air-conditioning unit is damaged or chafed. This minor damage to the wiring harness can be caused by vibration or rubbing of the harness against the metal parts of the air-conditioning unit. Over the course of operation, the wiring harness rubs up and down during normal driving conditions.

EGR Valve

Each Buick Century has a exhaust gas recirculation (EGR) valve on the engine. The valve is an integral part of the car's emission system, which helps the car burn fuel more efficiently. When this valve is not operating properly, the check engine light comes on and requires the valve to be changed out. If the EGR valve is not switched out or replaced, the Buick Century does not get the same fuel mileage as it would usually get during normal driving conditions.

Vacuum Leak

A check engine light can also be caused by a vacuum leak from one of the hoses that run throughout the engine of a Buick Century. The specific type of vacuum leak or where the vacuum leak is coming from can be diagnosed by the code that is issued with the check engine light. For example, the number on the code can tell the repairman what sensor needs to be replaced such as the front oxygen sensor. This code can also be caused by the engine misfiring.

Coolant Tempurature

The engine coolant temperature (ECT) sensor can be going bad or the coolant temperature can be too high. A ECT sensor has a high and low range. If the coolant that circulates through the engine and radiator falls above or below this range, the check engine light can come on and warn the operator of the Buick Century.

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