2004 Toyota Echo intermittent no start

My car engine light stayed on all of the time and I had intermittent no start issues. I took it to 2 different mechanics who indicated that it was the ECU. So, I got a new ECU and for about a week the car engine light didn’t stay on and it was fine. However, it has since happened again. Any ideas? Everyone seems totally stumped on this one. It’s a manual transmission if that makes a difference.

What codes if any?

Apparently none. Before the new ECU was put in the mechanic tried to find codes and it wouldn’t connect. None.

First off, if your check engine light is on take it to an auto parts store that does free code reading and post the results here. If the code reader does not register your vehicle and can’t communicate, look for a different mechanic. Look for recommendations. A good mechanic will repair the car so that it will communicate with the scan tool because that is an integral part of diagnostics. We could give you dozens of possibilities of problems that can be narrowed down significantly if the car can communicate. If the check engine light is on, there are codes stored and should be retrieved.

If the ECU can’t communicate to the code reader then the trouble is most likely with the power to the ECU. Unfortunately, the ECU was most likely replaced needlessly, but I could be wrong about that. I didn’t do the analysis. Just what I read here make me think that.

Or power to the DLC.

Thanks, the code reader wouldn’t communicate with the old ECU but I’m not sure if it will with the new ECU. The mechanic mostly likely didn’t check as he assumed the problem was fixed. For about 1 week after the new ECU was installed, I didn’t have the engine light on. It only reappeared after a week or so of having the new ECU.