I have a 99 Discovery II and have an ongoing problem. The check engine light is on permanently I think and when I run the codes its always the O2 sensor and gross emissions leak. I replaced the O2 sensors and fuel cap which fixes it for about 4 months and then it throw the codes again. This game goes on every year when I need to get it inspected. Any ideas why the O2 sensors continually need replacing along with the fuel cap???????? Thanks in advance.

 

So, what are the exact fault codes, can't help with out them?
Have you checked you 02 connections to make sure they are oil free, how about the harness check it for wear spots.
Gas caps rarely fix evap leaks, so get us some exact fault code numbers.

 

Mike,
Thanks for the reply. Codes are 0134, 0154 and 0455. Each year I go thru the same thing to get it inspected. A new Land Rover fuel cap keeps 0455 at bay long enough for an inspection. Can't say why or why it "goes bad". O2 are ongoing also. Thanks for your help.