Purchase advice Renault mode with electronics problem

Moin dear forum,I hope I’m right here with my concern. My partner and my littleness have enlarged us and need a small second car for them. She has 0 demands when it comes to the car and has put the mode in the head. We should not invest any money in the car, 2 years TÜV he should have, then she is satisfied. I had looked at some up to about 3300 € and always what was. No checkbook, totally lived or clutch in the a** ***. Yesterday one was online for 1800. A workshop in Cologne sells it in the customer order. Very well maintained, well equipped, already 190tsd down, but you didn’t notice him. Checkbook relatively complete and timing belts and clutch would already be made The “only” problem is that he sometimes doesn’t start, he shows something with oil pressure and battery weak then you have to get in and out of the key a few times and he goes on and drives clean. According to the mechanic the previous owner is The error memory said a problem with can bus engine control unit. He had recommended me a workshop in Bergheim which had specialized on control unit. An appointment would be free in 3 months. According to this company this is a small, common problem and will cost about 150 to 300 eur. I find unfortunately nothing on the Internet. What do you say? Tell the two the truth or is this all not plausible.