Chasing the codes! What now?
 

I have a 2003 LR Disco II with 132,000 miles on it.

History:
After about a year of flawless performance, I decided to add a K&N filter :(

The next day, I started throwing a MAF code. My LR mechanic in Denver told me what a mistake I made, and when cleaning the MAF and going back to a paper filter didn't work, I replaced the Mass Air Flow Sensor.

While driving home (150 miles) from the shop with the new MAF, I threw some new codes, this time gear 4 incorrect ratio, and system too lean bank 1&2. I never had theses codes before.

Here is what has been done to troubleshoot this:
Another NEW MAF sensor (just in case the other was bad)
Mechanic checked fuel pressure - was all OK
Replaced O2 sensors
replaced spark plugs
Inspection of hoses for leaks, and plug wires looked good

The truck runs great, but the System too Lean codes are still coming back withint 100 miles of resetting, and I get a gear ratio incorrect about once a week as well.

Any Ideas?

RE: Chasing the codes! What now?
 

Those 3 codes, 2 for lean and the tranny out of ratio are MAF related.
Go get them cleared again, if they come back call me, I am local to you.
303-862-7680

RE: Chasing the codes! What now?
 

Thanks Mike.

I have reset the codes numerous times (I have my own reader, like every LR owner should invest in), and have also reset them a few times after installing the new O2 Sensors (Ordered from British Atlantic and installed myself).

Because of your reply, I pulled the MAF today and used my MAF cleaner on it, even though it is brand new. I'll reset the codes and let you know what happens.

Troy

RE: Chasing the codes! What now?
 

ive seen all too often here people condemning mafs, they are not the only thing that can cause these codes. the lean codes are caused by too much o2 in your exhaust, generally from unmetered air in the engine(meterd by the mafs), but can also be caused by exhaust leaks, misfires, and most commenly vacuum leaks. the 4th gear ratio monitering code is caused when your ecm's calculated load value does not corrispond to the expected value from the road speed and trans gear ratio at a givin rpm. this said, when the three codes are combined it is usually the mafs, but it can very easily be a large vacuum leak, or even turbulance in the intake tube, both of which will cause a false mafs reading, check for vacuum leaks, make sure that your air filter housing is fully seated, with the tabs all in the right places, not bent in, you have a good o-ring sealing your mafs to the housing, that the idle air control valve port on the intake tube is not cracked or broken, and even that your wiring to the mafs is all intact with no loose pins or corrosion. do your checks first, then condemn something, but seeing as how youre on new sensor number 2 im doubting thats the cause, if its the right sensor