i have a 2004 polo 9N engine code AWY and i just noticed that the check engine light not showing on ignition and the fuel economy is getting worst. I know that the engine was replaced before i bought it and by the looks of it could  be a BBM, so could it be something to do with the ecu and how could i test it ?

The LED behind the fault light may have been obscured by something to hide a problem. 

A VCDS scan will be helpful to read stored fault codes. VCDS Lite, the freeware version is sufficient,  with a suitable FTDI cable which can be obtained cheaply.

On 11/01/2023 at 10:29, Pete1 said:

The LED behind the fault light may have been obscured by something to hide a problem. 

A VCDS scan will be helpful to read stored fault codes. VCDS Lite, the freeware version is sufficient,  with a suitable FTDI cable which can be obtained cheaply.

I already have a cable ordered but it will take another month to get here

On 11/01/2023 at 02:00, slimBHB said:

i have a 2004 polo 9N engine code AWY and i just noticed that the check engine light not showing on ignition and the fuel economy is getting worst. I know that the engine was replaced before i bought it and by the looks of it could  be a BBM, so could it be something to do with the ecu and how could i test it ?

Hello! Please could you tell if the engine swap from AWY to BBM needs any upgrades of the pins or firmware of VDO (or VDO itself)