So recently my 2010 XF Supercharged developed a rough idle condition, I found the cold air intake tube severely cracked and replaced it. Drove the vehicle about 3 days, then the check engine came on. Codes P0171/P0174. Local shop said the issue was caused by a leaking PCV system. They were not a Jag shop and made it clear they were not capable of making the repair. Is it possible the valves themselves are okay, and that it's just a hose leaking? Car is going to the dealer soon. Thank you.

 

A very common issue with these 5.0 engines are the PCV membranes. They’re located on the passenger side valve cover, the orange plastic wears and tears overtime and causes air to seep through. Another issue is the PCV hose that connects to the throttle body. The o ring located on the throttle body side of the hose shrinks overtime and allows air to enter causing a rough idle. I recommend replacing the entire hose due to the pressure crimps on the L shaped hose becoming weak due to age.
PCV Hose Part Number: AJ812235
PCV Membrane Part Number: LR041443
(Land Rover Part number due to Jaguar selling complete Valve Covers only, they’re all over eBay)

 

Excellent. Thank you. That is a big help. That is the area of the engine where the hissing sound is coming from, so it's definitely dumping air at or near those points in the diagram you provided.

 

my pcv pipe keeps coming off the pcv valve any ideas?

 

Put a new o-ring on, seat the front first and then attach it in the back