1998 Honda Civic P0505 code

Here’s a list of some of the other things that need to be checked before replacing any more parts. The throttle body for a clogged port or improper adjustment. The intake manifold gasket for leakage. The intake air hose for being loose and leaking. Vacuum leaks in general. Incorrect engine coolant temperature sensor output. On some models incorrect throttle position sensor output. Then you get down to the wiring from the computer to the idle air control valve or the computer.

I had done the first four suggestions and the temp sensor. The throttle position sensor I had not checked it yet and will look at that. Also I had pulled off an engine bracket to look at the wiring to the valve, it was said the bracket rubs the wires and they were fine. I also tested the voltage in the wire at the valve and computer.

Since I do not have a scan tool there is not much I can check, connector is clean. There is an error code for the temp. sensor and I have not seen it.

The intake is not leaking and all the vacuum hoses are tight. So since the error shows up less since I have cleaned the valve I am still leaning that it is faulty.

So I pulled off the IAC valve and sprayed it with WD40 and so far after a week it has not thrown a code.

Now I hear it is still throwing a code and did a few times this weekend. New valve?

yes change valve and let me know please

It took a while to get the part from the dealer, replaced it last night and driving it today the check engine light came back on and the same idle issue. Genuine Honda valve. This is of course frustrating.

what is the code for the check engine lite

The P0505 it has been every time no other.

Idle system problem Code: P0505
Idle Air Control Valve
Basically you need to check all the sensors that run to the PCM (vehicle speed sensor, coolant temp. sensor, air conditioning sensors, power steering pressure sensor, etc.) because the PCM adjusts the idle based on the info it receives from these sensors. You can do visual checks on the sensors to check for damage or corrosion. But make sure you check for vacuum leaks too.

The vehicle speed sensor is new as of 2 mo. ago. The speedo was erratic. Also I recently rebuilt the AC system. I have done visuals on all the sensors and checked all the wiring for any problems. Every bolt, hose and gasket on the intake side has been checked. I have done all the work on this car for the past 8 years including a clutch/transmission rebuild but this may have to go to a shop.