I think you need to go to another dealer, I had the same code.My gm dealer said glow plugs are not covered under the engine 100k warranty. So I bought one at car quest.
So far I disconnected the metal intake tube right after the turbo down to the air cooler radiator. Disconnected the 2 main plugs for the engine. Then was able to get to the #5 cylinder (I hope they are number like a short block 305) I pulled out the "U" clip and disconnected the one plug that hooks onto the glowplug like a motorcycle's spark plug. Then unhooked the plug that is horizontal.
All fine and dandy right?! Ok now how in the world do you get off that big bolt/harness/plug/etc. "thingy" that screws down around the the glow plug?!
X2, i had my #6cyl glow plug replaced 2 weeks ago. It was covered under the original 100k warranty but cost me $100. They also replaced the glow plug module too under my GMPP extended warranty for free. The GMPP would not cover the glow plug itself as it is considered a wear item like a spark plug. Not bad for $100 though.I think you need to go to another dealer, I had the same code.
Took it to the dealer, they popped a new glow plug in and I had it back in about 2 hours. Its definitely covered by warranty.
This is where i got in an argument with my dealer about comparing a glow plug to a spark plug, it is definitly covered by the 100k engine warranty. When my dealer told me it was a wear item i told them the crankshaft,cam and pistons are wear items too so i guess they are not covered either. How about the injection pump? I guess we are boned with that too, that is also a wear item. A glow plug is only used only for start up and even this is intermitten due to ambient temp, a spark plug is used repetatively and is essential in the start-up and overall running condition of the engine. Basically what i am saying is a diesel engine does not require glow plugs to operate but a gas engine will not run without spark plugs.Ok I have gone to multiple dealerships now and they are saying the glowplugs are like spark plugs and considered wear items. I wish I had some dealerships like you...
Ok, so I am stuck doing this myself. I have the wires and everything disconnected from the glow plug but there is a housing around the glow plug that has an electrical connector on it. The base has something that looks like you can get a wrench on it but the valve cover makes so where a box wrench will not fit. Is there a special tool or a trick to getting it out?