Hi..LR3SE V8 4.4 Lean 0171 Code gas mileage seems to be going down am at 12.1 MPG but have been doing short trips.Check Engine Light on for most of the year. Car running very good and brisk but had one Reduced Engine Performance come up.
Also when entering highway felt a touch of resistance a couple of times.
Engine Smoked and leaks attended to..Mass Air Flow Sensor replaced (OEM).. thermostat housing changed.Valve Cover Gaskets VVT Solenoid Seals..Air Filter replaced..dip stick tube repaired( new ones no longer made)
What to do next and likely to be cause? Mechanic is going to recheck the Valve Cover Gasket he says he thinks issue is on driver's side.
Thank you

 

You may want to look at This LOOONGG thread I think they tried almost everything looking to solve this same issue.

Jeff

 

But this issue is only Code 0171
that thread is including another code.

 

Also I bought the OEM Mass Air Flow Sensor from Atlantic British..it was a Delphi not a Denso.
I was told they carry both and are both OEMand Delphi was what they had in stock.

 

They are both codes for a lean fuel problem. Many of the diagnostic tests are the same.

 

Hoping the single code narrows it down to less possibile causes than with both codes.
I read the whole post I'm not sure if any of the 4 people with this problem there solved it.
It's mind boggling : (

 

The P0171 code is specific to bank 1 which is the passenger side in North America. These lean codes are a real pain! I’m going through this issue currently. I’m also part of the mess on that long thread. So far, no one has 100% and confidently resolved their lean codes.

Carb and Choke cleaner works great for finding vacuum leaks. It really helps narrow down the general area.

 

Thanks I'm going to keep trying. I was told by a Rover Parts guy it is usually the PCV Valve so I ordered one (always OEM just in case)
One guy in one tread mentioned a crack in his Catalytic converter was the solution : (

 

The PCV could definitely be the issue. When installing the new PCV. Make sure to lubricant the new O-rings with fresh oil. I would recommend replacing the hose on the PCV too at the same time. The O-ring on the hose could be bad or on its way out too.

These lean codes are a real pain to track down. I wish you the best luck and please reminder to share when you resolve your issues.

 

I didn't ask for new O Rings I hope they come attached to the PCV Valve from Atlantic British