You might want to consider www.discbrakesrus.com stainless lines. They are teflon coated and internally grounded which I'm guessing is why some lines throw codes and others don't.

 

Basically when you have a C1225 code it really can only be caused by a few items. Wiring and connectors are probably the #1 culprit followed by a bad ground, wheel sensor and finally the EBCM. My own opinion is you can usually eliminate a ground problem if only one code is being thrown and everything else in the car is working perfectly, but there are exceptions and it is not a bad idea to check the grounds. I started checking all the wiring and connectors one thing at a time and then go for a ride and believe me I went on a lot of rides. I finally figured out that say 95% of the time the codes were happening in the same locations on the road around my house and that is why the dealer couldn't find anything with their Tech II. Every time the car would set a code the radio would get very staticy and an instant later the code set.
This wasn't a random issue, it was every time I drove by these two locations. Somehow electrical interference was causing the code to set. I finally got hooked up with a GM master tech and explained to him what was happening and what I have done to diagnose the problem and what I have replaced. The very first question he asked me was if the car had stainless brakelines, after my reply, he said stop looking for a problem and just switch out the brake line. Did that Tuesday night, have driven a couple hundred miles and been by those two locations probably 10/15 times and no codes I can't explain why it was only the left front, but everything is good now.

 

My left front gave speed errors when I installed SS lines, grounded the line and the codes went away. Was it moving the lines around and making a better ground or the actual grounding of the line....I don't know, I don't care - no more codes.
No more codes means having AH which I like having on the street with the bad drivers around here.

 

Keith,

That is correct, it is a messy job. However, if you take the fluid out of the master cylinder first the system will draw in air as gravity pushes the fluid to the open line. The only way to then bleed the ABS system requires a Tech II to open and close the internal ABS valves so the system can be properly bled. Not letting in the air to begin with eliminates this issue. Hope this makes sense