My thought on the matter is "Never fix something that isn't broke." You stated "as part of routine maintenance" nothing you per did was routine. Switch to TOP TIER fuel and only do injector cleaning if there is a problem. TOP TIER - High-quality Fuel Performance Standard - TOP TIER™ (toptiergas.com) Hyundia recommends top tier fuel and it is not available ad a detergent to the gas tank at each oil change.

 

I always add a 50 mL bottle of Liqui Moly fuel system cleaner after each oil change. I only use TOP TIER 100% gas from Phillips 66.

 

Great news.... very glad to hear it.

The contacts inside the stick have to press over the tip of plug and secure into the groove. Sometimes the sticks need a solid smack with the palm of the hand to get past it. When you change them out you may also need to exert some force to pull the sticks off the plugs as well.

 

Coil sticks can be finicky. Are you sure they are pressed down completely? Push hard. If that doesn't work - I would put one coil back and see if that cylinder's code clears. I have a feeling you may have either the wrong coils, or some bad ones.

 

thank you so much for your insights
I did exactly what you said and problem codes are fine car is driving smooth again

i must have not pressed down hard enough on the back ones and just relied on the screw to secure them in place.

i really appreciate your time to respond

 

Being snarky Maybe the codes mean you did this too early, my manual says:
Spark plugs Replace every 156,000 km (97,500 miles)

 

This would have nothing to do with throwing those codes. Just for anyone else reading this thread, you can change plugs and coils whenever you want. Just be sure to buy good quality products and install correctly.