Engine malfunction indicator flashes yellow on my P12

Hello friends, something always seems to go wrong, unfortunately!! I was surprised that my 1.8 Traveller combo suddenly has such a thirst, well I find the 10-12l consumption a little too much. And constantly I try to drive slowly, but it didn’t help. And this evening suddenly a yellow indicator started to flash, to which it is said in the instructions: fault indicator. Another explanation in the user’s manual to the car says it could be the engine control unit That is also responsible for consumption and for acceleration etc…. At the ADAC I learned that this is a lack that the seller must fix in any case (I had bought the car 3 weeks ago – EZ 2003/116 PS). Actually I had to go to a NISSAN workshop to confirm the damage and then to the dealer – and it will certainly cross the border….naja Has one or the other already had problems with it. t and if you have to pay it yourself, how much can it be?? Greetings and thanks, Jumbo_747