Land Rover Repair: 2000 disco II lean condition, mass air meter, thankyou john

Question
I recently purchased a 00 disco II and after driving it for about 2k miles I noticed alot of spark Knock. I tried octane booster and better gas with no luck. Then I noticed the service engine light was not working when the key was turned on someone removed the bulb. I checked the codes with my scanner and got lean conditions for banks 1 & 2 . What should I do now. Also I got a noise that was not there when I bought it. It sounds like a bad timing chain or something. Its most noticed at idle. Thankyou John

Answer
If they removed the check engine light to conceal a problem who knows what else is waiting to be discovered?

The most common cause of a lean condition is a bad mass air meter, but that's just a guess.  I suggest having a shop with proper LR test gear look the car over carefully.

I have no idea what to tell you about the timing chain noise.  Timing chains are really never noisy on Land Rover V8 motors in my experience.