Jaguar XF Won't Start After the Battery Is Disconnected? Smart Key Not Found
Why a Jaguar XF can refuse to start, even with two good keys, after the battery is removed or replaced: what happens inside the car, the warnings you may see, which models it affects and how we help.
Short answer: if a Jaguar XF will not start after its battery was disconnected or replaced, the car has often lost its link with the keys. The keys and the new battery can be perfectly fine. We come to the car anywhere in Hamilton and the Waikato to help, with no tow to a dealer.
What happens to the car when the battery comes off
A modern Jaguar XF is run by several control units that keep settings in memory and talk to each other and to the key. When the battery is disconnected, replaced or goes flat, those units can lose their settings or stop talking to each other. The car then no longer recognises its keys and will not start, even though the keys and the battery are in good condition.
Jaguar's own service bulletins describe this kind of fault on the XF: the engine fails to crank, the message Smart key not found appears, and the car may not lock or unlock from the key. Jaguar also says the car's modules sometimes need to be taken back to a default state before anything is replaced.
What you may see
- The warning Reposition smart key and press start button in the instrument cluster, as in the photo above
- Smart key not found or Unable to find smart key
- A start button that does nothing, or only clicks, and an engine that will not crank
- The key not locking or unlocking the car
- Other warnings on the dash, while the touchscreen and lights still work
Why two working keys do not help
The fault is in the car's key system, not in the keys, so both keys usually fail in the same way. This customer had two keys and the car still would not start. Changing the battery in the key fob does not change that either.
Common situations
- A new battery fitted at home, at a battery shop or by a mechanic
- The battery disconnected for other repairs
- A jump start, or a flat battery
- A car left sitting until the battery died
- Battery cables taken off during a service
Which cars it affects
| Car | Years | What we know |
|---|---|---|
| Jaguar XF (X250), after the 2012 update | About 2012 to 2015 | Where owners and repair shops report this most. Jaguar's own bulletin lists the XF 2013 to 2015 for the engine not cranking and the Smart key not found message. |
| Jaguar XF (X250), early cars | 2008 to 2011 | Reported as less often affected. If an early XF stops recognising its keys after a battery change, it is still worth a call. |
| Jaguar XF (X260) | 2016 on | Owners report similar key recognition faults after a battery change. |
| Jaguar XJ (X351) | 2010 on | Listed in the same Jaguar bulletin as the XF. |
| Jaguar F-Type | 2014 on | Listed in the same Jaguar bulletin as the XF. |
| Other European cars | Many | BMW, Mercedes, Audi, Volkswagen, Volvo and Land Rover among them. Many need their battery management set up again after a new battery, so ask us if your car will not start after one. |
What not to do
Do not keep disconnecting and reconnecting the battery to see if it clears. It is not a dependable fix, and the car can end up in the same state. Do not buy a replacement module or a new key until the cause is confirmed. Jaguar's own bulletins say the system should be checked before parts are replaced.
How we help
We come to you, so the car does not need towing to a dealer. Send us a photo of the message on the dash, and the year and model, or call us. We help Jaguar owners across Hamilton and the Waikato, 8am to 6pm, seven days. More on our Jaguar locksmith page and our Jaguar XF page. You can ask for a quote or call 0210 239 9777. If a key is lost or damaged, see our pages on lost car keys, smart key replacement and spare car keys.
Sources
Jaguar Land Rover technical bulletin JTB00357NAS1, 2 November 2015 (Engine will not crank / Smart key not found displayed), and Jaguar service bulletin SSM70138, December 2013 (Smart junction box issues, XF X250). Model years beyond Jaguar's bulletins come from owner and repair-shop reports, not from Jaguar.
Common questions
Why won't my Jaguar XF start after a battery change?
The car's key system can lose its link with the keys when power is cut. It is often the car, not the battery or the key.
What does smart key not found mean on a Jaguar XF?
The car cannot detect a key. After a battery change it can happen even with a good key and a fresh key battery.
What does reposition smart key and press start button mean?
The car is not recognising the key. After a battery change it can keep showing this even when the key is next to the start button.
Will a new key fob battery fix it?
Usually not. If the fault started when the car battery was disconnected, the problem sits in the car, not the key.
I have two keys. Why does neither work?
Because the fault is in the car's key system, not the keys. Both keys fail in the same way.
Which Jaguar XF years are affected?
We see it most on XF models from about 2012 to 2015. Jaguar's bulletins also list the XJ and the F-Type.
Does my Jaguar XF need to be towed to a dealer?
Usually not. We come to the car anywhere in Hamilton and the Waikato.
Does this happen on other makes?
Many European cars react to a battery change. If yours will not start after one, send us the details.