I am a long time Range Rover owner and recently purchased a 2003 Disco,e help the Service engine light went on on my way home from picking up truck and the code is 4th gear ratio, po734......any ideas? I cleared it, drove about 200 miles then I had the green "m" and "s" light on dash and the red indicator light on shifter was blinking, and the speedometer was blinking "0".I turned off truck, restarted it and those lights went off, but about 50 miles later the service engine light went back on showing the same code.....i know that land rovers have gremlins, i need a little help finding them and eradicating them.....
thank you

 

Sounds like a battery or alternator or cable problem.

If that doesn't take care of it, you might have a bad mass air flow sensor, that can cause the the 4th gear ratio code.

 

I had the same problem... I replaced my battery and it went away...... Good luck with your new truck! This is a great forum, because everyone here has probebly had the same problem... great advice from really knowledgable people... i've learned a hell of alot just from reading the posts....

 

X2 on all of that, the D2 needs a tip top battery dues to so much extra electronics, and the cables on the battery and around the underhood fuse box need to be clean and tight. The tranny ecu does not like low voltage, it also exchanges info with the main engine ecu, and tells you when it thinks engine does not have enough power for gear selected, frequently MAF and plugs and wires can figure in this. MAF can be cleaned with a spray made for MAFs, but should be done when engine cold.

 

New Battery, check cables, clean maf (when cold).....thanks a lot...
I used this forum a TON for my 1997 Range Rover......kept it running till 195,000 miles, the help here assisted me in changing over to coils, bypassing some ecu faults, numerous electrical issues,fuel injectors, fans.....but I just had to let it go when it overheated towing a trailer while in the Adirondacks in upstate ny......oh well.....we hunted for a Disco, but I was unaware of oil pressure issue....truck has 94000 miles, I purchased from original owner who maintained it at local LR dealer for $4000 ......Is there anything I can do to prevent the failure? I read that it happened early in the life of these trucks.......I saw nothing on mine ........and I believe its IN the range.....
thanks again to all..

 

Mechanical oil PSI test would be a good start. Some owners install an oil PSI gauge. Many owners add an Ultra Guage which is driven by the OBDII port and can dispaly things like coolant temp more precisely so you can see temps rise before overheat begins. About $70. 15W40 Shell Rotella oil. Decent filter. See https://landroverforums.com/forum/di...estions-46975/.

 

thanks again,visually battery looks pretty sad, i have an oil pressure gauge in garage so those two things are first, i will do temp next and change oil......