This is trouble code for your coolant sensor. It has most likely failed to get this error to come up. Replacing it should solve this problem. You will have to locate this and replace it. I would tell, but I dont know the location for this vehicle. Alot of times they are located near the thermostat housing. Hope this helps.
Trouble code P0500 means: Vehicle Speed Sensor A
Trouble code P0117 means: Engine Coolant Temperature Circuit Low Input Replace the coolant temp sensor
After googling it is determined Code P0420 ( Catalytic converter effeciency below threshold)
Code 45 on a Honda Civic means the car is not getting proper fuel flow. All the major fuel components should be checked such as the map sensor, oxygen sensor, and fuel pump.
To fix a ratio on a 2000 Honda Civic transmission, follow the procedure stipulated in the users manual.
You will need to change the brakes and rotors on the Honda Civic to see if that fixes them. If not, take the car to a mechanic and have them fix the problem.
2004 Honda civic not giving good gas mpg
new gaS CAP
You don't fix it, you just replace it. After replacing it get an alinement.
The only thing you can do to them is change them.
Replace the fuse.
i think there's a recall