Citroen C2 - will not start after changing the battery

[Birdynumnum55]

Hello folks. I hope that someone may be able to advise here. I've just changed the battery on my Citroen C2 1.1 VT (09 plate)
The car now will not start. I hear a ticking noise when I turn the key (throttle body?) and nothing else. The message on the dash initially read 'Anti-theft activated'
(or something along those ines) but now says the car is on Economy Mode (despite the new battery) Does the ECU need to be reset...or is this something else.
Thanks in advance for any handy hints and tips

[Paul-R]

Did you use the proper disconnection/reconnection procedure? If not follow the steps here viewtopic.php?t=61997

[Birdynumnum55]

Hello Paul. I tried the procedure...but it didnt work for me. I can still open and close the car doors using the key fob (not manual - using the buttons)
However, when I get into the car and turn the key, the electric windows do not open. The car message still states 'Economy mode' with the battery image still flashing ( despite the fact its a new battery. Could it be a fuse perhaps. It's driving me nuts!

[Paul-R]

I can still open and close the car doors using the key fob (not manual - using the buttons)

I don't quite understand this. Are you saying that you can remotely lock and unlock the car using the buttons on the key fob? It's just possible that the sensor coil for the inhibitor system around the ignition column lock has coincidentally failed at the same time as changing the battery. Do you have a second key to try?

[wheeler]

Does it have a sensodrive gearbox? if so is it showing N on the dash?
If the keys is not recognised (or just the aerial gone down) the engine would still turn over as normal on the starter.

[ozvtr]

The Mk2 C2's starter is run from a relay in the BSM (engine bay fuse box). This relay is indirectly driven from the CAN BUS.
In this case the ignition switch sends a signal to the BSI (glove box fuse box) and the BSI puts a signal on the CAN BUS to run the starter.
While I'm not sure, an "anti-theft" error might stop the starter relay in the BSM from being energized?
The starter solenoid is connected to pin 2 of the yellow connector of the BSM.
It is possible to remove the connector from the BSM and short it onto the positive terminal of the battery.
Caution: the gearbox needs to be in neutral.
If the starter runs (and the engine turns over) the problem is not the starter.
I don't think it's the starter but you need to eliminate that. After all you did say you heard a click when you turned the key.

Don't worry about ECO MODE. That just means the system has reduced electrical consumption and cut certain systems of power (including the windows?). It does this normally after 30 minutes of inactivity and the key on.
You CANNOT get the car out of ECO MODE without starting and running the engine!!!

The 'Anti-theft activated' message is a worry. This signal is generated by the BSI and means that it has not received a correct response from either the engine ECU or the transponder in the key (one or the other) .
It's unlikely to be the key (unless you have fiddled with the key?) or associated devices from the key to the BSI. Most likely a problem with the BSI or engine ECU.
In that case most likely faults are: a "scrambled" or damaged BSI. Or damaged engine ECU.
It is possible that engine ECU has been damaged by installing the battery...but highly unlikely! Unless the battery was initially installed around the wrong way??!!
Again it's possible that the BSI has been damaged but even less likely than the engine ECU. The BSI is still demonstrating that it is working. I.E. running displays and lighting "n stuff"!

So IMHO it's either the engine ECU is damaged, or the BSI is "confused".
Given those two choices I would continue on with the BSI resets!

Really, you need to get a scan tool on it and find out where the 'anti-theft' message is coming from.

Now, it still could be one of a thousand things (including Wheeler's sensodrive lock out) but the above is only based on you saying that you "only changed the battery" (correctly) AND DID NOTHING ELSE. AND that Anti-theft is still activated!

[Birdynumnum55]

Thanks to all for the advice.
Paul-R - I've tried with the second key - the result is the same. The central locking still works..and I can switch the lights on and off. Nowt else!

Oz-VTR I that I'll try the BSI resets......then if all else fails - a phonecall to the garage.-