I have 2011 duramax, a week ago my check engine light came on so I plugged in my scanner and gave me a glow plug for #5 cylinder. I tested it and it was bad. I live in a small town so I was only able to purchase 4 glow plugs, so I only replaced the glow plugs on the odd cylinders. Yesterday my check engine light came on again and the code for that was #2 glow plug. Is this common? Is there a relay bad? Haven't checked that glow plug yet waiting for new ones to show up. Is there something else wrong cause the truck only has 50000 miles?

 

Update on this? Was it just bad plugs or an issue with the truck?