Changed the plugs in my 2010 6 4cyl this afternoon, along with cleaning the throttle body and dropping in new engine and cabin air filters. Plugs are Denso Iridium, carefully gapped to 0.040", per the instructions from the parts counter at my local Advance. Car fires right up and runs smooth as glass (125k miles, btw), but the CEL is on. Thoughts?

 

Is everything plugged in properly?

Are you sure the spark plugs are the correct plugs? Do they look the same?

Disconnect the battery, press & hold the brake pedal for 5 minutes.

Make sure the ignition key is removed, all the lights are turned off & the doors are closed.

Re connect the Battery, start the car, make sure lights, radio, heater are all off, let it idle for 4 or 5 minutes, take it for a steady drive & see what happens.

 

Drove the car again this morning, for around half an hour, followed by an hour parked. Since then, the light is out and hasn't returned. My best guess is there was some TB cleaner still in the intake, fouling a sensor, that has finally burned off.