Hello

I have a Honda 1989 model and on the ecu it has a small clear panel with numbers 8,4,2,1 on it with a red light behind each one.
When car is started numbers 4 and 2 are on

What does that mean ?

Regards

 

It means that you have a Code 2 and a Code 4. I am not sure what the 2 is, but the 4 is a Crank Position Sensor failure. You need to find a FSM for the model vehicle/engine that you have and the codes will be listed in the "Fuel" section.

 

What is the FSM ?

 

I'm pretty sure that's a binary counter and if it's only showing 4 and 2 lit, and this doesn't change, it's code 6 - ECT (engine coolant temp). Either the sensor is bad, disconnected or the wiring is open.

 

Factory Service Manual.

 

I did change the coolant temp sensor and did measure 5 volts on the plug.
it seems the car does not overfuel anymore and starts easier.But the lights on ecu are still on,can i clear or reset it somehow ?

 

Disconnect the battery (or unplug the ECU... all three plugs) for 30 minutes, reconnect and see if the lights come back on.