Peugeot 206 1.9 diesel

hmm ,i work on these cars a lot and never had one with this light out ,check you havent a wire off somewhere or a fuse for engine management out .

Economy mode usually comes on when the computer senses a low charge on the battery and conserves power to start the vehicle.
1. If you can start the car by jump starting from another vehicle with its engine running then you know your battery is the problem. In some cases when you completely drain a battery you have issues with them ever after until they fail completely.

2. If you cannot jump start from another vehicle then turn everything off and disconnect the negative and then the positive lead on the battery terminals and leave it for 10 minutes. Then connect it back up again (positive lead first and then negative lead last) and put the key in the ignition and turn on the ignition but do not start the car. Leave it there for 5 minutes and then turn the ignition it off. Then try starting again.

3. You have not mentioned if there are any other warning lights being displayed on the dash which you have not mentioned in your question. Please check this carefully because it is also relevant to this problem if there are other warning lights displayed.

Economy mode means you should charge your battery firs as it might be almost flat.

neural safety switch, in proper gear, if auto trans move shifter to
a different gear then back to park retry

Type your problem in on google.com

There should be NO WARNING LIGHTS on while the vehicle is running. If ANY warning lights come on while the vehicle is running, SOMETHING IS WRONG.

check the wires in the rubber boot near the door hinge, the alarm wires are there and it is a known peugeot weakness

the starting problem has nothing to do with a new exhaust system being fitted,, it could be the car alarm cutting off the fule pump though,,, try reseting the alarm it may have been upset by the work done on the exhaust,,,

you must fill the fuel filter housing with diesel to eliminate air pocket. if you don't have diesel, fill it with automatic transmission fluid. it will smoke for a few seconds, but it will run so fuel pump can catch up. don't touch throttle for a few seconds till you know that it is running on diesel and the tranny fluid is all used up.