Eco Mode - turns over but wont start

Hi Can anyone help, I recently brought a 2006 55reg C3 nice car bit of history but the key was broken and stuck together with tape. I brought a new case and transferred the circuit board and battery, the new key locks and unlocks the car no problem but when I try to start the car it stays in eco mode, turns over ok but wont fire.

Any tips greatly appreciated

Hi Omega

Inside the old key case there is a transponder chip, that also needs transferring to the new key. It's a small 'chip' a few millimetres long and clips into the side of the plastic case next to where the blade comes out.

The transponder chip controls the car's immobiliser (part of the anti-theft system), without it the car won't start.

I hope you still have the parts from the old key?

There are some words and pictures regarding the C3 key fob, remote board and immobiliser chip in this topic for the fob (here).

I have the new style flip key, the transponder is on the circuit board rather than separate in the old fixed key.

I have had the key checked out by a locksmith and its working fine, CL and transponder. I charged the battery although the car was turning over fine and it still didn't start, I left it on charge and tried again and now it has started.

My biggest worry now is I don't know what the fault was so it could appear at anytime now.

Thanks for the responses I will keep you informed if it happens again, I'm going to get a diagnostic check, can anyone recommend anyone round Walsall - Aldridge - Birmingham areas?

Thanks