C4 Shine Plus Key not recognised

[Pointypitt]

Hi - new member here, so hello.

I have an issue with our C4. Keyless stopped working and got a bit temperamental recently - then the car stopped recognising the key. I changed the key battery, but still the same issue.

I also have similar issues with the other key - it would be weird if both key fob batteries failed at same time so I’m guessing something else…

Could it be the car 12v battery?

Stop/Start has not been working recently, and then car is short trips with everything heated on full (Scottish winter weather!) and is 3.5 years old, so it could be starting to get depleted.

Any thoughts?

Cheers!

[Pointypitt]

Update…. New car battery didn’t help.

But it really felt like it would - I got an airbag light and a brake warning before changing the battery.

Everything cleared after the battery change - just still the key issue.

Bizarre!

[GiveMeABreak]

Hi

Very possibly, little time for the battery to keep everything running, yet alone recharge any depletion - especially with the systems that run when the engine is off, like alarms, fob proximity detection, Head Unit, RCD circuit etc etc.

Some ECUs are very strict on minimum voltage to operate correctly, so can have adverse effects on vehicle systems.

I suggest a good 48 hour trickle charge with a Smart Charger at least. But don't forget to reset anti-pinch and reinitialise fobs if changing or disconnecting battery:

BSI Reset / Battery Disconnect / Reconnect Procedure

Failing that, and if you're still getting issues with starting or unlocking - it may be the Hands-Free unit that need sorting (hopefully under warranty) - which I strongly suggest you make use of whilst / if you have it.

[Pointypitt]

Thanks for this. I will try and then let you know!!

Appreciated!

[Pointypitt]

Can I ask a further question?

…. It now transpires that all the issues tarred after a bottle of Lucozade was spilled in the passenger footwell… Are there any modules located around that area that could be giving the symptoms I’m seeing?

Just wondering if any liquid has gotten in somewhere it shouldn’t. Or maybe it’s just a coincidence.

Thanks again!

[GiveMeABreak]

Hi, with this latest info - yes!

On right hand drive vehicles there is usually an airbag wire that travels under the (Right Hand Drive) passenger floor to the passenger seat. This can be a source of problems years down the line from all the stepping in and out - but if you've had a fluid spillage, it's possible this may have gotten into the connector. But be careful with airbag wiring for obvious safety reasons.