To start out this is my first Land Rover, 1999 Discovery II 48K miles. Got it cheap but need to get rid of the CEL. The codes are P0171, P0174, and P1590. The seaching I've done leads me to believe that P0171 and P0174 are being caused by the Mass air flow sensor. But I'm lost on the P1590. The ABS, Hill Descent, and Traction Control lights are on as well. I have aftermarket pads and I'm considering changing them to factory pads. Any suggestons would be appreciated.

 

To have the MAF failing you also need a code for a 3rd gear tranny problem, sounds more like you have either a plug wires problem or a carbon problem causing misfires. How many miles on your truck, how many on the plug wires, have you decarboned it at all, do you use Premium gas?
Mike

 

It only has 48,000 miles, The plug wires and spark plugs were replaced 4,000 miles ago, and I run premium. I've done more research and the 1590 code seems to be related to the ABS system. Has anyone had this problem before?

 

ABS has always been a Rover problem but it doesn't show up on the CEL, it will only store a code if the 3 Brake warning lights are on, ABS, H/D and T/C. I believ 1590 is an engine related issue.
Mike

 

Ah the terrible trio of ABS lights. I'm not certain about the code though, but I think it's a shuttle valve fault. As for the lights, look closely at the wheels speed sensors to make sure they are seated properly. If they are, it's the ABS modulator. (shuttle valve is internal & a common failure)

 

The new MAF showed up today (from Drivewire.com only $135 with shipping) I installed it in less then 5 minutes and it cleared all of the codes. Still trying to figure out the Treo of lights? I went to the dealer they hooked it up to their machine and told me its a shuttle valve problem and that power flushing the brake lines has 65% chance of fixing it, otherwise its $1,600 to replace the ABS modulator. If the flush doesn't work where can i get a replacement ABS modulator? I found a guy on Ebay who will rebuild it for $350 plus shipping, has anyone rebuilt their modulator? Thanks for the help so far.

 

There is now a repair kit available to repair the shuttle valve, might want to look into that, it is pretty cheap.
Mike

 

anyone have any experience with the shuttle valve repair kit? is it easy to install and does it work?