BTT: I am battling with a similar problem.

I drive a Peugeot 207. It started with the car cutting power, which came with the 'Engine Mgt System Faulty' sign. After paying through the eye of the needle to get it fixed, my mech took it to a car wash, unsolicited, and got the engine compartment washed too. 3 days later, the 'Depollution System Faulty' came up and the car began choosing when to respond to kick-starting. The car eventually refused to start sometime in April and has remained grounded after a pug expert diagnosed the ECU as fried. April till date, we have not been able to get a matching ECU, BSI, and key.
The car has been a wonderful car only that its maintenance and parts have been worrisome. I am even contemplating selling the car after fixing it, but it would break my heart to sell unhappiness to someone else. Pls help Siena.

Pls help.

Siena: Not strictly true that the Peugeot / Citroen BSI can't be recoded. With the correct knowledge and software, they're coded all day long. In Nigeria however, your options with regards coding are somewhat limited.

You'll need the BSI, ECU and ignition key from the same donor car, with the same engine as your own car. With regards your altered mileage, your Peugeot 206, like most new models (BMW and Mercedes-Benz are the same) stores mileage data in the ECU or BSI. Older cars stored mileage data in the instrument cluster. This means you can lift the cluster from a lower mileage car, and as soon as you plug it into your car, and power it up, your own mileage will appear.

The mileage can't be altered, as far as I know.

Have you tried replacing your original BSI unit? If yes, does the engine now start, and has your mileage reverted back to what it should be?