V8 4.4 p1158/60 codes, anyone had similar and cured please?

[Scorpion8]

Hi,
  I have recently bought a late 2000 4.4 X5 with 139k miles which has an issue with the engine management light coming on with codes 1158 and 1160.
I knew about the light issue as I bought the car off a family member who in turn had bought the car from my boss, so I have known the car and how it's been looked after for the last 8 years.
The codes relating to fuel adjustment have lead me to look around for perished breather pipes of which I found 2 and repaired but still the same.
The car runs fine if light on or off so no noticeable difference there.
The car drives about 80+ miles before light comes on after reset.
The 1158 code appears first as pending, followed by the 1160 code.
The 1158 code can trip the light on its own and have 1160 pending but generally they both trip the light.
The light seems to only come on when idling, wether it's been idling for 10 minutes or at start up, light doesn't seem to come on when engine at higher revs.
Because I'm getting the code for one side first it makes me think the maf is not the cause.
I had a garage scan for more in depth info but they only found a code relating to timing adjustment which has only been once as far as I know.
I've read up lots on here and was hoping maybe someone had a similar experience and was able to share how they cured it.
From what I've read I'm thinking the egr valve is not to blame as engine runs smoothly. Maybe a vent hose perished at the back of the engine where I haven't been able to reach fully. Or the inlet manifold seals, or as simple as an o2 sensor playing up? Any experiences or thoughts of what direction I need to look in (throw money at!) would be welcome.
Thanks.

[X5-D-Sport]

Well... for my 3 penneth worth, I've had just about every electrical gremlin there is on an X5...

Firstly, you know the vehicle... so that's a good starter point..
Secondly, I'd not rush out to spend your HARD EARNED money ££$$££$$...

I would buy an OBD scanner that can reset/zero alert codes.. I got a really good one from Flea-Bay for about £50, and it clears nasty messages... and if the message is valid, it will soon come back..

there are a lot of little pipes buries around these engines... and also it may possibly by a joiner/union or 3 way joint leaking... the plastic bit can crack or become brittle with age - I found this out the hard way when changing pipes, and everything they push onto drops off lol...

I have found that if there are BIG sensors failing i.e. Lamda / EGR / MAF etc, they are often/sometimes  easiest to detect, as the vehicle will generally run like crap. or the diagnosis is much more specific...

Don't rush out to spend the cash just yet, it's probably a bad hair day for your machine..

have a great day.
Grant B

[Greydog]

Remember codes are indicating the symptom not the cause, they show a fueling imbalance so work through the fuel system simple things first. Fuel filter when was it last changed? Vacuum leak somewhere? Possible clogged cats? Clean the MAF.
Check the fuel return system there is a valve in the engine bay, also check the fuel cap if it isnt sealing it will cause issues.
+1 with Grant, I got the BMW 1.4.0 scanner invaluable for sorting silly nigles that a Dealer or any Garage would charge £££££ for.

[themoog]

Check the two crankcase breather pipes at the top rear of the engine. Numbers 4 and 5 on realoem.com breather system diagram. If its one of those split or collapsed the buy from a Land Rover specialist for circa £7 for the pair.

[Scorpion8]

Thanks for your replys gents. I think I shall try to get to the back of the engine for a proper look at breather pipes when weather and time allows and also have a go at cleaning the maf.
As the engine appears to drive fine wether light on or off I don't suspect anything major looming and so might not find out where to look until symptoms start showing. If it wasn't for the light coming on there is no way I'd think I need to be looking under the bonnet.
I have bought a lead and software off eBay for more in depth diagnostics but the Chinese English installation instructions are proving challenging so not up and running yet!