Citroen C3 / C5 Aircross Forums

Hi

One of my key fobs has stopped working after I've changed a battery and I know it's not the battery as I've checked it in the spare key.

I think it needs reprogramming to the car but all the guides I find online are cars with an ignition and mine is keyless.

Does anyone have an idea how I can do this?

Thanks

Keys that are not used for a while or the battery goes flat loose their memory and have to be reintroduced to the car. That doesn't mean they need reprogramming just reintroducing.
To do this, do the following:
If car has keyless go to 12. below:
If car has ignition switch:
1. Insert key in ign switch and turn to position 1
2. Now press either the lock or unlock button for 10 secs.
3. Release the button.
4. Turn key to OFF.
5. Remove key.
6. Exit car
7. Test locking function
If working
8. Unlock car
9. Enter
10. Start engine.
11. If not repeat process.

If car has keyless function:
12. Place key fob against the flat section on the left side of column shroud.
13. Press lock or unlock button, continue as for ign key procedure above from 3. above.
If this doesn't work then key needs reprogramming.

How strange is that, this morning I decided to change over to my second keyless key. It's is locked away when not in use and I cycle them every 4 months. Got in car, it's kept in garage unlocked and pressed start button on dash. Got message on dash KEY NOT DETECTED. Held it against the flat detent on left side of column shroud but didn't press any buttons just to see what would happen. Removed key from against detent, pressed start button on dash, engine started. The fob was tested at destination all functions working.

Also, make sure you keep your keyless fobs in a screened case / pouch (Faraday) when in the house / garage to prevent theft (signal relay receiver/ transmitter devices) if you don't already do this. They're only a few £s online to buy.

I had an interesting problem this week. Wife complained her fob wasn’t working. I replaced the battery in her fob and as I have no clue how old the batteries are, thought it a great idea to change mine too.

Wife’s fob still didn’t work. Trouble is, neither did mine. Spent a good while swapping batteries, tried another new set, did all the procedures to re-initialise the keys, nothing worked.

In desperation, took the car to the local dealer who did all the same things and also failed. Advised me to book it in for full diagnostics.

Keen to NOT pay their £92 per hour costs, for what seemed like it had potential to be several hours work plus parts…….I found a local auto locksmith in Wigan who within 2 mins confirmed neither of the keys were working, as no frequency was detected on his tablet from either key. He advised the quality of the original keys isn’t the best, but never seen two stop working. He quickly sorted me out with a far superior key which he programmed to the car and even cut me the internal hard-key to go inside the fob. Left my old keys with him to investigate and within an hour he called me to say they were repaired. Internal PCBs had separated so no power getting to the circuit boards.

No idea how this happened, I was really careful changing the batteries and this simple task should not be harming the internals. Anyway, I now have three working keys and one of them of far better quality than the originals that I’m using and only charged me for the new key, no charge for the repair of the old fobs.

Interesting thing though, he informed me all Citroen keys are type 4A, but within this type there are around 8 different onboard chips and you need the exact match to pair to the cars ECU or it won’t work. Citroen’ are always a bit fiddly to sort out compared to other cars and it can be a very long wait sometimes for the diagnostics to “pull” the PIN number from the ECU. He tried two replacement 4A keys, before deciding to generate a brand new key onto one of his more expensive, durable “generic” keys which has a different very powerful chipset and is capable of taking programming for virtually any car.

Total cost was £110. You look at the cost of getting a replacement key from Timpsons, who are pretty good usually, they want between £205 and £300 and they claim this to be 50% less than the dealer costs!

I welcome the fact that they are more 'fiddly' as this makes it more challenging for thieves.

The actual fob for a hands-free C3 Aircross is £271 inc. VAT
The Key Blade (Cut on order to specific vehicle) is £41.24 Inc. VAT.

This doesn't include key programming to the BSI, but takes a minute or so to do at the dealer who may not charge you if you have bought the items from them.

If you have Hands Free entry and Starting, make sure you keep ALL your fobs contained in a Faraday pocket to prevent relay theft.

Yeah, but more fiddly and temperamental for the professionals means unpredictable issues and increased time and cost to resolve genuine issues. Not the best situation really, but agree with making life harder for the light fingered amongst us.

The main cause of the problems with the fobs is that they contain a lot of sensitive circuitry and microswitches that are very vulnerable to being dropped. So unless you are both 'butter finger' types, your fobs may of been part of a bad run.

I have both my spares in custom fit leather cases like this, for that very reason, as I often carry too many things when leaving the house and trying to lock the door. I got so annoyed with myself when dropping them that I bought these and now have the fob buckle fastened to my belt loop and then the fob hangs into my trouser pocket, which is additional safety in case the very secure clip ever did fall apart. The leather case also provide another layer of protection against drops.

No, that is certainly not the issue, not with my wife and I at any rate. I've spent many years building and repairing computer's in my spare time and more recently phones too, so I am well versed in working with sensitive PCB's and chips in static sensitive environments. My key is similarly protected and hangs in my pocket on a belt loop. My wife's key is in faraday pouch within a protected pocket within her bag, as she uses it only very occasionally.

These keys have been treated no differently to all the other keys we have had during the last 25 years of driving cars with similar keys and over the years I must have changed a good many batteries. The only issue I ever had was changing batteries in a VW key fob for my Mk7 Golf GTi where the batteries I bought were a duff set, but this was diagnosed swifty (by me) and it started working again right away when I tried another set.

The 'bad batch' theory could be possible, but I have no way of knowing how the previous owner treated these keys as the car was new to me in Feb when I bought it. It is an ex-motability car, so it is possible the previous owner was less dextrous through no fault of their own and the keys were not subject to the same level of TLC they get now.