Ten days ago I changed the transmission oil and filter. It was done by a mechanic who, because he was a friend’s father, decided to do it with him. More cheaper of course. He has experience since he is 70 years old. Since I had seen many YouTube videos on how to do this job, I saw that it had its important things to do. I sent him some of these videos and I don’t think he saw them. According to him, he had done that job on another similar car the week before. Well, he did the job but he did not measured that the amount of oil he put in was the same as what was dropped. According to him, when he put the oil with a pump under the gasket, when it started to bounce was the limit. He did not touched of any fuses and did not measure the temperature of anything. Now the car, although it works well and does not make noises every time when starting the first 10 seconds, the maintenance signal flashes. How bad did he do it? can it cause problems? or will everything be fine? or do I need to do something. Thanks in advance
When you say maintenance signal do you mean the check engine light or the maintenance reminder?
The CEL is supposed to come on when you start the car as part of the normal lamp check procedure. (Of course all the lights are supposed to come on for the same reason).
Normally if the light stays on there’s a stored trouble code. Most places like AutoZone can check for stored codes for free.
Unless he unplugged or damaged a wiring harness, there’s no way a fluid change could cause CEL. In other words it’s unlikely he caused the issue.
Check transmission fluid and oil level and scan for codes.