Unlock and Start With a Dead Key Fob

If your Renault Trafic III (X82, 2014–2021) remote stops locking or unlocking the doors, the usual cause is a flat fob battery — and the good news is the van still works. Renault confirms that with a weak remote battery you can still get in and start it using the fob’s built-in key blade. Here is how, plus how to swap the battery.

First: Will It Still Start?

Yes. Even when the remote battery is too weak to lock or unlock by button, the key still starts the van — the immobiliser reads the key’s built-in transponder, which needs no battery. So a dead fob battery leaves you locked out of the buttons, not stranded.

Get In and Start With a Flat Fob Battery

1. Release the key blade. Press the button on the fob and the metal switchblade key flips out of the housing.
2. Unlock the driver’s door with the blade. Use it in the driver’s door lock to open the van manually (on some vans the lock sits behind a small cap on the door handle).
3. Get in and start as normal. On key-start vans, turn the key — the transponder is recognised without the remote battery. On keyless-start (hands-free) vans, press the start button with your foot on the brake; if it doesn’t detect the fob, hold the fob against the start button or card reader and try again.
4. Replace the fob battery as soon as you can so the remote locking works again (below).

Replace the Remote Battery

• Open the fob case at the slot with a small flat-blade screwdriver.
• Swap the coin cell, matching the type and polarity marked on the back of the cover — Renault simply specifies the same or an equivalent cell, so check the marking on your own fob rather than guessing. The cell lasts roughly two years.
• Clip the cover back on firmly (and tighten the small screw if fitted) so the contacts seat properly — a loose cover is a common cause of a fob that works only intermittently.

After changing the battery the remote works straight away; there is no owner resynchronisation step on this generation. Note that if the 12 volt battery has been disconnected or replaced, the van’s ACCESS mode resets to its default setting.

If It Still Won’t Respond

A fob that only works now and then usually has a tired cell or a worn battery clip — reseat the cell and make sure the cover clips tight. If both keys stopped working at once, suspect the central-locking supply rather than the fobs: check the relevant fuse and that the receiver has power. A key that unlocks manually but won’t start the van points to an immobiliser/transponder fault, which needs a diagnostic read.

Frequently Asked Questions

Will my Renault Trafic start with a dead key fob battery?

Yes. Renault states the van still starts and locks/unlocks even when the remote battery is too weak — use the built-in key blade to open the door, then start as normal because the immobiliser transponder in the key works without a battery.

Where is the emergency key on the Trafic fob?

It’s the metal switchblade blade folded inside the fob. Press the release button and it flips out; use it in the driver’s door lock to open the van by hand.

What battery does the Trafic key fob take?

Renault only specifies “the same or an equivalent” cell and says to check the type and polarity marked on the back of the cover — it’s a standard coin cell lasting about two years. Read the marking on your own fob before buying, as fobs differ by trim and year.

Do I need to reprogram the fob after changing the battery?

No. On the Trafic III there is no owner resynchronisation step — the remote works as soon as a good battery is fitted. Full key re-coding (for example after a lost key) does need dealer or specialist equipment.

Is this the same on the Fiat Talento, Nissan NV300 and Vauxhall Vivaro?

Yes. These are the same X82 platform with the same fob and key, so the get-in-and-start method and battery swap are identical.

If a warning light or fault code came up alongside the key trouble, look it up on autodtcs.com. To clear the service reminder after a service, see our Trafic service indicator reset guide.