Land Rover Repair: Just failed my emissions test!, land rover specialists, obd ii scanner

Question
Hi John I wanted to see if you could steer me in the right direction here. My 2000 Disco II failed its' emissions insp. and the dealership is telling me that a valve that sends "extra exhaust back through the engine to burned off" is malfunctioning.  They want to charge me about $500 to do the repairs.  I dunno if this is really a big repair or not.  I have a basic repair manual and would really rather do this myself if possible.  Whatya think...any advice on this much info?  Thanx!

Answer
The emission control system is sort of complex to test, and your explanation does not point to a specific part.  Several parts might fit the description you gave.  My advice is that you pay the $500 because the description is ambiguous.

There is no way for you to verify the operation of the system in your Rover if you did attempt a repair.  You'd have to swap a part, adn drive 3-400 miles to see if the light cleared.  If it didn't, you'd be back to square one - replace something and drive some more.

Land Rover specialists have equipment to test this stuff, and that's the only way to get an efficient proper repair.  By "proper equipment," I mean an Autologic or T4 Land Rover test system.  Dealers and specialists will have that stuff.  An owner or a  general repair shop with a generic OBD II scanner is not likely to get a good result on a problem like this.