CTS is registering new codes after I installed two new spark plugs and 2 new coils


Asked by Sep 28, 2018 at 04:03 PM about the 2005 Cadillac CTS 3.6L RWD

Question type: Maintenance & Repair

Are we plug the computer into it it said cylinders 1 & 2 or
misfiring so I bought two new spark plugs and 2 new coils.  
Got them installed and crank up the car and it runs way
rough for now and we plug the computer back up and now
it's saying other different cylinders are misfiring now and a
whole bunch of other codes I didn't know if the new coils
are creating more power and tripping out the system or
what I don't know what to do

5 Answers


Did you mix up the wires when you replaced the coils?


I don't believe we messed with any wires at all


All we did was loosen up several bolts on intake lifted up just enough to do the coils and spark plugs on cylinders 1 and 2. Now the car is running on 2cylinders instead of 6

3 people found this helpful.

Same thing happened to us. We replaced coils, spark plugs was still getting misfire, rough run.. took it to our mechanic. The last thing we didn't replace. The wire harness that connect the spark plugs.. smh. That's all it was. Hope you fiqured it out by now but in case you didnt hope this helps

1 people found this helpful.

If you did figure it out and it was the wires, what was it? My 04 cts 3.6 has been doing the exact same thing. I have replaced the plugs it read off bad, the fuel injector, checked wires. And seems to get rougher more and more after I replace something. Just like to know if I need to replace the coils, injectors, and plugs all at the same time for it to run smooth again? It started with just a code reading bad fuel injector and now it being a huge pain.

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