One problem related to gas recirculation valve (egr valve) has been reported for the 1999 Buick Century. The most recently reported issues are listed below.
Cpsc# i1280196a. 1999 Buick Century. Consumer got an engine for his car. The consumer stated the very day he purchased the engine and had it installed, the engine light illuminated. The engine was tested and the consumer was informed, the problem was with the egr valve. The consumer purchased the egr valve. However, the engine light remained on. The technician who installed the engine, stated the cylinder heads were damaged.