Starting Problems help and thoughts required

I purchased a c3 pluriel 16 2004, for my partner and the vehicle has the following problem.

More often than not, when I try to start the vehicle, the key turns and nothing happens. The vehicle is in the N position with my foot on the brake pedal. Then the vehicle shows a spanner and the engine light on the dash and the vehicle goes into auto mode. The vehicle will not start nor can I now select or change gears with the selector or paddles.

I then have to take the plus terminal off the battery wait a minute and reconnect and then turn the key so the dash lights come on, but not to start position with my foot on the brake pedal. This then resets the gearbox and the vehicle goes to the 1st gear after a few minutes, whereby I can then select neutral.

The vehicle then starts no problems.

I have purchased a new battery and it still has the same issue.

I was thinking now of replacing the ECU?

Any thoughts would be really appreciated. Thank you.

Hi suisse

Then the vehicle shows a spanner and the engine light on the dash and the vehicle goes into auto mode

Get lexia clone and install that to a laptop and read the diagnostics. This will give you codes and information about the engine light and why the car won't start.

With this information you can start looking at the right parts to test or change.

I was thinking now of replacing the ECU?

I wouldn't do this unless you know its faulty....