These instructions apply to the Infiniti QX30 (H15) 2016-2019.
For other models, please choose your vehicle here.
The Infiniti QX30 (H15, 2016–2019) was built on the Mercedes GLA platform, but the key you carry is pure Infiniti — the three-button Intelligent Key (smart proximity fob) shared across the Infiniti range. When that fob starts working only from arm’s length, throws a key-battery warning in the cluster, or refuses to lock the car at all, the cause is almost always the flat coin cell inside. The important detail on this model: it uses a CR2025, not the CR2032 you’ll find in a lot of other cars — so don’t buy the thicker cell out of habit. Here’s how to tell a dying battery from a real fault, the exact cell, how to open the fob without scratching it, and why cutting a brand-new key is the one part of this job you can’t do on the driveway.
How to Tell the Fob Battery Is Dying
- Shrinking range. You have to stand right next to the QX30 — or hold the fob against the door handle — before it will lock or unlock. This is the classic first sign.
- Passive entry stops responding. Walking up and pulling the handle no longer wakes the car; you find yourself pressing the fob buttons instead, and even those need a close range.
- A key-battery warning. The QX30 shows a low-key-battery message in the instrument display when the fob voltage drops, along with a warning chime.
- Push-button start hesitates. If the car struggles to detect the key when you press START, holding the fob against the button often works — a telltale sign the transmitter is running on a weak cell.
A coin cell in an Intelligent Key typically lasts two to four years. If yours is around that age and showing any of the above, fit a fresh cell before you start suspecting the receiver or immobiliser.
The Battery You Need
The QX30 Intelligent Key takes a single CR2025 3-volt lithium coin cell. That is a common size — sold in supermarkets, hardware shops and phone/watch counters — but it is thinner than the CR2032 that many other fobs use. The two look almost identical and a CR2032 will even wedge in, but it is the wrong thickness and can distort the contacts, so match the number printed on the cell you remove: CR2025. Buy a good-quality branded cell; budget cells sag under the brief current the transmitter draws and can give poor range even when new.
How to Change the Battery
- Release the emergency key blade first. Press the small catch on the fob and slide the metal mechanical key straight out. This blade unlocks the driver’s door if the car is ever fully unresponsive, and pulling it out also exposes the seam you need to open.
- Find the two small slots in the split line that runs around the fob where the emergency key came out. These are the leverage points for splitting the case.
- Protect the case, then pry. Wrap the tip of a small flat-blade screwdriver in a strip of tape or thin cloth so it won’t scratch the chrome trim. Insert it into one of the slots and gently twist to pop the seam, then work along the split line until the two halves separate.
- Note the orientation, then lift the old cell out. On the QX30 fob the CR2025 sits positive (+) side facing down, against the spring contact in the base — so the printed “CR2025” face is what you see, and the plus symbol is hidden underneath.
- Drop the fresh cell in the same way — positive down — and press it under its retaining clip until it seats flat.
- Click the halves back together around the whole seam, then slide the emergency key blade back in until it latches. Test lock, unlock and passive entry before you put the car back in service.
⚠️ Get the polarity right. The cell goes in positive-side-down on this fob. A coin cell fitted upside down won’t power the transmitter and can quietly discharge against the wrong contact — if in any doubt, copy the exact orientation of the cell you took out.
Make Sure It Took
Stand back a few metres and lock, then unlock, the QX30. Full range should return straight away, and passive entry should wake the car as you reach for the handle again. Any key-battery-low message in the cluster usually clears once the car reads a healthy fob — sometimes immediately, sometimes after the next start or short drive.
If a Fresh Cell Doesn’t Fix It
- Re-check polarity and seating. Positive must face down, and the cell has to sit flat under its clip against clean contacts — a cell that is cocked or loose gives intermittent range that mimics a fault.
- Confirm it’s really a CR2025. A thinner CR2016 will rattle and lose contact; a CR2032 forced in can spring the holder. Use the correct CR2025.
- Wipe the contacts. Finger grease or light corrosion on the terminals is enough to cause dropouts — clean them with a dry cloth or a cotton bud.
- Rule out the car battery. A weak 12 V battery can make the QX30 slow to recognise the key and throw odd warnings. If the car itself is sluggish to wake, that — not the fob — may be the real issue.
- Still dead with a known-good cell? If the fob shows no life at all, the transmitter may have failed — a fob-replacement job, though that is rare next to a flat or upside-down cell.
New Key or Spare — Why It’s a Dealer Job
Swapping the coin cell keeps the fob’s existing coding, so nothing needs reprogramming and the key works the instant it powers back up. A new key is a different matter: the QX30’s Intelligent Key has to be registered to the car’s immobiliser with a diagnostic tool, the emergency blade has to be cut to the car’s key code, and blank fobs are ordered against the VIN. Because of the platform’s security, adding a spare or replacing a lost key is a job for an Infiniti dealer or a properly-equipped auto-locksmith — so keep the battery in your spare fresh too, and you’ll never be down to a single working key.
Frequently Asked Questions
What battery does an Infiniti QX30 key fob take?
A single CR2025 3-volt lithium coin cell. It’s thinner than the CR2032 used by many other cars, so check the number on the old cell rather than assuming.
Is it a CR2025 or a CR2032?
The QX30 Intelligent Key uses a CR2025. A CR2032 is the same diameter but thicker and can distort the contacts — fit the correct CR2025.
Which way up does the battery go?
Positive (+) side down, against the spring contact in the base of the fob. If you’re unsure, match the orientation of the cell you removed.
Do I need to reprogram the key after changing the battery?
No. A battery swap doesn’t touch the fob’s coding, so it pairs with the car straight away. Only a brand-new key needs programming to the immobiliser.
How long should a QX30 key battery last?
Usually two to four years. Leaving the fob sitting close to the car, where the passive system keeps waking it, tends to shorten that.
Can I still drive the QX30 if the fob battery is completely dead?
Yes. Use the emergency blade inside the fob to unlock the driver’s door, then hold the fob against the START button — the car can read the key at close range even with a flat cell, so a dead battery won’t strand you.
If the fob stopped responding suddenly right after the car battery was disconnected — rather than fading gradually — the cause is more likely the pairing or a stored fault than the coin cell. You can look up what a stored code means on autodtcs.com.
Independent guide — not affiliated with Infiniti. Always follow your official service manual and safety precautions. Read our full disclaimer.