Ok so my 2001 S Type 3.0 Auto came up with PO171- PO174 lean codes , short term fuel trims high readings ! using a rubber pipe stuck in my ear I ran the engine and listened for an air leak ! this appeared to be coming from the engine breather rubber hose below the injection manifold at the back of the engine (Part number XR8 45730 ).This usually requires the removal of the inlet manifold and injection manifold , also loads of expensive gaskets ! ,I should know i have done both of my S Type's for coils and plus in the last few months !, and my 1999 ones PCV valve .So this time i thought i would replace the rubber hose without removing the manifolds ! ,and yes it can be done ! its a little bit tight and fiddly but i did mine in @1.5 hours !.First I removed the wiper arms ,and windscreen scuttle , then the front scuttle steel brace ! this may not need to be removed but does give better access.Next remove four 8mm headed nuts that hold down the wiring loom cover to the rear of both rocker covers, you will need this loose to gain access to the breather!.Next remove the 8mm headed bolts and stud that hold the fuel rail pressure regulator crash protector , the metal round tube around the rail sensors outside .
There are some pipes that will need moving to get a clear view ! , the next bit is the tight bit ! remove the 10mm nut that holds a braided earth to the rear of the left hand cylinder head this is a squeeze between the bulkhead and the wiring loom cover (that's why it needs removing from its mountings ) ,once the earth is removed then the stud has a 13mm nut remove this stud/nut this releases the 90 degree steel oil breather pipe !(Part number XR827668)note this pipe comes complete with the lower rubber elbow!.Now by twisting the oil breather pipe and a long screwdriver lever off the old rubber pipe ,mine was split on the under side so did not see any fault when i fitted my coils !.Place the new rubber pipe onto the metal oil breather hose lube the inside of the outer end and work it back on to the PCV valve , re assemble in reverse order.Its not the easiest job but a lot cheaper than all the gaskets and chances of causing more leaks!.Now i wish i had taken some pictures to help but did not have time ! .This job was done with normal hand tools , although i used an air ratchet at the back of the cylinder head to speed up the job ! it still needed cracking off with a spanner anyway !.