Can anyone direct me to where I can find DTC Code Definitions for my 1997 Land Rover Range Rover 4.0? I get 4 trouble readings of (2) P1193 and (2) P3999. Cannot find these codes anywhere. Any help regarding the codes or otherwise would be greatly appreciated.
Happy Holidays everyone!

It looks like P1193 is the Oxygen Sensors. Are there 2 or 4 and does anyone know where they are located? Thanks again.

 

Your 1193 is for 02 sensor heater circuit open down stream.
The other code I don't see.
How many miles on the truck and how is it running?

 

It's got 148k miles and runs great. MPG 13-15. This is the oxygen sensors correct? I assume I would have to replace all 4 since I don't know which are faulty. What does this mean, "02 sensor heater circuit open down stream"?