Start the Car With a Dead Key Fob Battery

If the remote on your Jeep Renegade (BU, 2014–Present) has stopped locking the doors or the dash flashes “Key Fob Not Detected,” the coin cell inside the fob has almost certainly gone flat. The good news is that the Renegade’s Keyless Enter-N-Go system is designed for exactly this moment: a dead fob will still start the car and still get you inside, because the transponder chip in the fob is powered by the vehicle, not by the battery. This guide walks through both, then shows you how to fit a fresh cell.

Start the Renegade with a dead fob battery

The start button has a backup antenna directly behind it that reads the fob’s passive chip from very close range. When the button reads “Key Fob Not Detected,” do this:

1. Sit in the driver’s seat with both doors closed and press the brake pedal firmly.
2. Take the key fob and turn it so the nose end — the side opposite the emergency key blade — faces the dashboard.
3. Press that nose of the fob flat against the ENGINE START/STOP button and hold it there.
4. With the fob still touching the button, push the button through the fob. The Renegade reads the chip and cranks.
5. Once it fires, set the fob in the cupholder or door pocket — the engine keeps running for the trip.

There is no need to pry the start button out of the dash, despite what some forum posts suggest. The close-proximity read is the factory-intended method.

Unlock the doors with the emergency key

A dead fob will not lock or unlock the doors by radio, so you use the hidden steel blade instead:

1. Find the small release latch on the side of the fob and slide it while pulling the emergency key blade free of the fob body.
2. On the driver’s door handle, the lock cylinder sits behind a small plastic cap. Gently pry the cap off with the tip of the blade or a fingernail.
3. Insert the blade and turn to unlock the driver’s door.
4. Slide the blade back into the fob so you don’t lose it.

Will the alarm sound?

If the Renegade’s security alarm is armed, opening the door with the blade can trigger it. Don’t panic — once you sit in and complete the dead-fob start sequence above, the system recognises a valid key and the alarm clears.

Replace the key fob battery

The Renegade fob takes a single CR2032 3-volt coin cell:

1. Slide out the emergency key blade first — the notch it leaves is the leverage point.
2. Split the two halves of the fob with a coin or a small flat screwdriver in that notch.
3. Lift out the old CR2032 and drop in the new one, positive (+) side facing the same way as the original.
4. Click the halves back together and refit the blade. Test lock/unlock from a few steps away.

Frequently Asked Questions

My Renegade has no visible keyhole — where is it? It’s hidden under a small cap on the driver’s door handle. Pop the cap off and the cylinder is underneath; it accepts the emergency blade from inside the fob.

Does the engine keep running once I let go of the fob? Yes. The proximity read only has to happen once at start. After that you can put the fob away for the rest of the drive.

Will this work if the Renegade’s main 12V battery is also flat? No. The dead-fob start only solves a dead fob; if the car’s own battery is flat the dash won’t light up at all and you’ll need a jump start first.

Which battery does the Renegade fob use? A CR2032 lithium coin cell. Keep a spare in the glovebox — they’re sold in any supermarket.

Why did the fob die so fast? A fob parked within a couple of metres of the car wakes constantly and drains in months rather than years. Store it away from the vehicle overnight to extend cell life.

If a warning light stayed on after the dead-fob episode, you can look up the trouble code on our sister site autodtcs.com.