I installed a set of Gibson stainless steel headers about a year ago. I've had an exhaust leak on the driver side since the day I installed it due to an egg shaped collector on the header. About 8 months later I got a P0135 and P0155 heater circuit malfunction code. So I called gibson and they sent me a new header with a good sealing, round, collector. I also replaced both O2 sensors with new Motorcraft sensors to avoid future problems. I checked my connections to my O2 sensors and they are locked solid and no nicks in the wires at all. Could the design in the headers cause this code so show up? Is there a value that can be changed in an SCT Chip to correct this problem? Any help will be greatly appreciated b/c I can't look at this stupid check engine light anymore.

 

If you check what the codes are indicating, it's their heater circuits are open.
Have you checked the fuse supplying them and for burnt or bare wires that may have blown the fuse?
Should not have to go this long with this problem. It makes for poor fuel mileage and cold start warm ups.
Good luck.

 

Ive looked the wires up and down, there are no blown fuses or nicks in the wires. I have reset the code a few times. Sometimes it comes back in 30 miles, sometimes I can go more than 300 miles before it pops up again. Ive also had the check engine light disappear a couple of times then come back the next day. Im curious if its the way the exhaust runs through the headers that could cause a change, although it doesnt make sense to me.