E.G.R. system
The EGR valve must function properly and no leaks can be evident in the pipes and connections. Replace any damaged part.
Clean the pipes, valve and connections from time to time.
Do not touch the EGR pipes while the engine is running or until they have cooled off after the engine is stopped:
EGR pipes are extremely hot during engine operation and for a while after operation. Touching them could cause severe burns.