Land Rover Repair: Check Engine, land rover discovery, jockey pulley

Question
Hello,

I have a 1999 Land Rover Discovery.  My check engine light is on.  I have had so many repairs done to this vehicle.  A year ago, I went to the dealer because the check engine light came on.  They performed the EFI test and it came up with PCODE P0130-Bank 1 02 Sensor FLT and P0171.  They replaced bank 1 up stream oxygen sensor and clear codes and reset adapations.  Five days later the light came on.  I went back to the dealer, the vehicle was also rumbling and vibrating and also had a squealing noise.  The code revealed PCODE p0303, p0305: Misfire Cylinder #3 & 5.  They changed out the spark plugs (cost me $400).  

In addition to the above repairs the exhaust manifold gasket has been replaced, upper radiator hose and system flush and jockey  pulley replaced.

With all that said....my check engine lights have come on again.  My brother in law wants to take a look at it.  He has always worked on him and his wife car with success.  Can you please give me an idea of what can cause this light to be coming on again?  

Answer
You really need to look at the stored fault codes and then perform the tests that are appropriate to the codes.

You can access all the dealer service information for your Rover for an $18 daily fee at www.landrovertechinfo.com  You may want to go there and download the testing information before you start.