These instructions apply to the Cadillac CT6 (2016-2020).
For other models, please choose your vehicle here.
The Cadillac CT6 (2016–2020) full-size sedan is a keyless car: the fob stays in your pocket and the CT6 unlocks and starts hands-free. When the fob’s coin cell dies the dash warns “No Remote Detected” and the START button goes quiet — but GM hides a battery-free backup in the center console, so you are not stranded.
Start the CT6 With a Dead Fob: the Transmitter Pocket
The CT6 does not start by touching the fob to the button. There is a transmitter pocket with an antenna coil built into the center console — on the CT6 it sits in the face at the rear of the console, behind the cupholders rather than under the front armrest. Resting the fob there lets the car power and read its chip even with a flat battery.
- Get in first with the metal blade (see below) and take the driver’s seat.
- Locate the transmitter pocket in the back face of the center console.
- Slide the fob into the pocket with the key ring up and the buttons facing toward the front of the car.
- With the CT6 in Park or Neutral, press the brake pedal and hold it.
- Press the ENGINE START/STOP button as normal. The engine starts because the console antenna has read the transponder in the fob.
Leave the fob in the pocket for the trip; the chip only needs reading once at start-up.
Unlock the Door With the Emergency Key
A dead fob will not work the remote locks, so use the metal blade hidden inside it.
- Slide the release latch on the fob and pull out the emergency key blade.
- The driver’s door lock cylinder is concealed behind a cover on the handle — ease the cap off with the blade, or use the access notch beneath the handle.
- Insert the blade and turn to unlock. If the alarm sounds, starting the car with the fob in the pocket stops it.
Why the Immobiliser Still Lets You Start
The fob’s transponder chip is passive — it takes no power from the coin cell and is energised by the antenna’s field. The radio link used for normal hands-free entry is dead, but the console pocket sits directly over the back-up antenna, so the immobiliser still recognises the fob and the CT6 starts. It is a deliberate fallback GM builds into every keyless model.
Replace the Coin Cell
The pocket gets you moving; change the battery the same day so it does not happen again.
- Pull the emergency key out to expose the seam in the fob.
- Twist the two halves apart using the slot or a coin.
- The CT6 fob uses one CR2032 3V lithium coin cell. Note the old cell’s orientation — positive (+) usually faces up — and fit the new one the same way.
- Clip the halves back together and refit the blade. Hands-free entry should work straight away.
Frequently Asked Questions
The CT6 still shows “No Remote Detected” with the fob in the pocket. Reseat the fob fully, ring up and buttons toward the front, then press the brake firmly before START. If it still fails, a weak 12V battery can produce the same warning — check that next.
Where is the pocket exactly? Unlike the ATS and CTS, the CT6 puts the transmitter pocket in the rearward face of the center console rather than under the front armrest. Look behind the cupholders.
Can I hold the fob on the START button instead? No. The antenna for the backup is in the console pocket, not behind the button. Use the pocket.
Does the metal key start the engine? No. It only unlocks the driver’s door; there is no ignition barrel. Starting is always via the pocket and the START button.
Is the plug-in hybrid CT6 any different? No. The PHEV uses the same keyless fob and the same console transmitter pocket as the petrol CT6.
If a warning light stayed on after you got going, you can look up the exact fault code on our sister site autodtcs.com to see whether it relates to the keyless system or something unrelated.
Independent guide — not affiliated with Cadillac. Always follow your official service manual and safety precautions. Read our full disclaimer.