Engine Light code 4 and code 8

[KD2229]

Dear All,
I have the following problem in my small port. Please help!

I have the check engine warning light on, after I short the termainal E1, code 4 and code 8 is indicate.

Lets deal with Code 8 first, cold air temp. sensor, as I change my air filter to a after market one, since then I dont have it, but it should not appear and should be "no show" for the check engine light unless I short E1 terminal for inspection. So, I guess this one I can ignore it.

Code 4, water temperature sensor, I have check the wiring and the Ohm for the temp. sensor, everything seems to be normal. But the check engine warning light still on. So, I have no idea, thank to help me on this one or any other possible reason.

Of course, I have reset the ECU by removing -ve terminal on the battery after I did the check.

Thank you very much!