These instructions apply to the Maserati Quattroporte Mk6 (M156) 2013-2024.
For other models, please choose your vehicle here.
When the smart key for a Maserati Quattroporte (M156, sixth generation, 2013–2024) starts working only from arm’s length, fails to unlock the car on the first press, or throws a low-battery warning on the dash, the cause is almost always the little coin cell buried inside the fob. The M156 Quattroporte ships with a single style of key — the keyless smart fob (the M3N-7393490 remote family shared with the Ghibli and Levante of the same era), with a slide-out emergency blade tucked in the end. There is no separate flip-key variant to worry about, so every car in this generation opens the same way. Here is exactly how to swap the cell yourself, why the polarity matters, and where the DIY line stops and a dealer visit begins.
How to Tell the Fob Battery Is Dying
- Shrinking range. You find yourself standing right beside the car, or almost touching the door handle, before it will lock or unlock. This is the earliest and most reliable warning sign.
- A dash message. The Quattroporte shows a low key-fob battery notice on the instrument cluster display when the cell is getting weak — the manufacturer builds this alert in precisely so you are not caught out.
- Passive entry gets flaky. Keyless walk-up unlock and the push-button start may need a couple of tries, or you have to hold the fob directly against the marked spot on the steering column to start the car.
- Cold-morning dropouts. A cell that is nearly flat sags further in cold weather, so intermittent behaviour that is worse first thing on a winter morning points straight at the battery.
A CR2032 in a Maserati smart key typically lasts two to four years. If yours is around that age and showing any of the symptoms above, fit a fresh cell before you start suspecting the car’s receiver or immobiliser.
The Battery You Need
The M156 Quattroporte smart key takes a single CR2032 — a 3-volt lithium coin cell, 20 mm across — and nothing else. It is the most common fob battery made, sold in any supermarket, hardware shop or pharmacy. Buy a good-quality branded cell: bargain-bin coin cells sag under the brief high-current pulse the transmitter draws and can give poor range even when they read as “new” on a meter.
Method — Opening the Quattroporte Smart Key
You will need a Torx T6 driver (the screw is genuinely that small — a normal small flat-blade will chew it) and, ideally, a plastic pry tool to part the halves without scratching the case.
- Slide out the emergency blade. Press the release catch on the fob and pull the mechanical key blade straight out. This exposes the fixing screw underneath.
- Undo the lateral screw. With the T6 driver, loosen the single small screw on the side that clamps the two side covers together, and set it somewhere safe — it is easy to lose.
- Remove the two side (silver) covers. They lift away from the body of the remote once the screw is out.
- Split the case. Gently part the top and bottom halves of the inner (black) housing. Work around the seam with a fingernail or plastic tool rather than forcing one corner.
- Lift out the circuit board. The PCB sits on top of the battery; ease it up carefully so you can reach the cell underneath. Note which way the old cell faces before you disturb it.
- Fit the new CR2032 positive (+) side DOWN. On this fob the printed “+” face sits toward the board / away from you as it seats in the holder — the opposite of what many people assume. Match the orientation of the cell you removed.
- Reassemble in reverse. Refit the PCB, close the black halves, clip the silver covers back on, drive the T6 screw home — snug, not forced, the threads are into plastic — and slide the emergency blade back until it latches.
⚠️ Get the polarity right. This fob takes the cell positive-side-down. Fitting it the wrong way up means the key simply will not transmit, and leaving it inverted can slowly discharge a good cell — so always copy the orientation of the battery you took out.
Check It Worked
Stand back a few metres and lock, then unlock, the car with the buttons. Full range should return at once. The low key-battery message on the cluster normally clears the next time the car reads a healthy fob — sometimes instantly, sometimes after one drive cycle. Test walk-up keyless entry and push-button start too, since those rely on the same cell.
If a Fresh Cell Doesn’t Fix It
- Re-check the polarity. Positive-side-down on this key — fitting it the wrong way is the single most common reason a “new battery” changes nothing.
- Reseat the PCB and cell. If the board is not sitting flat, or the coin cell is not firmly under its clip against clean contacts, the fob will behave as if the battery is still dead.
- Wipe the contacts. A smear of finger grease or light corrosion on the terminals is enough to cause dropouts; clean them with a dry cloth.
- Warning still showing? Give it a couple of drive cycles to clear. If a known-good cell still leaves the fob unresponsive, the remote’s transmitter may have failed, which is rare next to a simple flat or upside-down cell.
New Key or Spare — Why It’s a Dealer Job
Changing the battery keeps the fob’s existing coding intact, so nothing needs reprogramming afterwards. Cutting and coding a new or spare key is a different matter: a blank Maserati smart fob must be ordered against the car’s VIN and then paired to the immobiliser with factory-level diagnostic equipment. On a car of this value most independents send it to a Maserati dealer or a specialist locksmith who has the right tooling. The practical takeaway: keep the battery in your spare key fresh as well, and you are never down to a single working fob.
Frequently Asked Questions
What battery does a Maserati Quattroporte M156 key take?
A single CR2032 3-volt lithium coin cell. The same cell fits every sixth-generation (2013–2024) Quattroporte smart key.
Which way up does the battery go?
Positive (+) side down. That is the opposite of many fobs, so do not guess — match the orientation of the cell you removed, or check against the holder as you seat the new one.
What tool do I need to open the fob?
A Torx T6 driver for the small lateral screw, after you slide out the emergency blade. A plastic pry tool helps you part the case halves without marking them.
Do I need to reprogram the key after changing the battery?
No. A battery swap does not touch the fob’s coding, so it works straight away. Only a brand-new key needs programming to the car.
How long should a Quattroporte key battery last?
Usually two to four years. Heavy remote use, or leaving the fob sitting close to the car so the keyless system keeps waking it, shortens that.
Can I still start the car 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 marked reader spot on the steering column and press the start button — the car is designed to start from a dead fob battery, so a flat cell will not strand you.
If the remote went dead suddenly right after the car’s 12 V battery was disconnected — rather than fading over weeks — the pairing rather than the coin cell is the more likely culprit, and a stored fault code can help confirm it. You can look up what any related code means on autodtcs.com.
Independent guide — not affiliated with Maserati. Always follow your official service manual and safety precautions. Read our full disclaimer.