I have codes on a 2003 land rover Freelander, the code are P0420, p1472, P1477, and P0174, how do i repair them.

Answer: These code you have on your Land Rover are the catalytic converter is inefficient, and engine running lean. These codes can be related to each other, or they can be separate. It all depends on if the codes where set at about the same time, or not at all around the same time. A scanner that shows history data of the code would show when the codes set.

The way to diagnose these codes is the look at- live data with the engine running and the look at the oxygen sensors readings. The computer determines if the engine is running lean or rich, and if the catalytic converter is functioning normally.

The oxygen sensors can cause all the problems, or the engine running poorly can cause them. Most likely the catalytic converter is failing and causing the other codes, but a good diagnostic would be needed to confirm this.