Charge unly to 60 pnds,MOdel wl 6166 26 gls. I change the pressure switch look for air leaks seems to ok

These codes usually means the ECU thinks the air/fuel mixture is too rich. Recheck all the connections on the new parts you fitted are fitted correctly and not loose. There are a lot of other sensors that can trigger these codes. I would suggest taking it to a good mechanic so they can actually look at it and drive it to find the issue.
The codes mean...
P0172 = System too rich (Bank 1).
P0173 = Fuel Trim Malfunction (Bank 2).
P0507 = Idle control system RPM is higher than expected.

E4 Outdoor activation of low pressure switch/ less suction pressure.

Check back pressure, which should be 60 PSI when ambient temp 98 degree.If not Short of gas- find leak and arrest. And do gas charging. Even due to indoor coil dust blocked also e4 arise. Clean the coil and reset it

if theres no air leaks it may need a pump rebuild. The pressure switch start stop is adjustable, look under the cover

Hey Joe,
Are you sure it's the hydraulic oil low pressure or is it the engine oil low pressure light? Check the engine oil for being low, over full, filter change, right type of oil, leaks, air filter, spark plug, clean air intake, battery getting a good charge, if that stuff is ok, then find your oil pressure switch and change that out.
But it if it is the hydraulic oil light, check for leaks, that is a high pressure system so don't put your hand by hydraulic leaks use cardboard or something to check for leaks, a pin hole leak can cause severe damage to your skin from a high pressure injection from fluid.
Let me know if this helps and we can go from here

Cbillgreene:

Your compressor is leaking air somewhere between the compressor head and the tank. With the compressor running, feel carefully around the ends of the tube that leads from the compressor head to the air tank. You will probably feel some air leaking around one end or the other. If so... remove the tube and find out which packing has failed.

The 2000 model year Accent adopts a different "pressurized" leak check system capable of detecting a 0.020" (0.5 mm) diameter leak (previous Hyundai systems detect a 0.040" [1mm] diameter leak using engine vacuum). The new system uses a Diagnostic Module for Tank Leakage (DM-TL) to close and pressurize the fuel evaporative emissions system. The DM-TL replaces the fuel tank pressure sensor and the canister close valve from previous systems. Other significant changes were made to the system logic, including several new diagnostic trouble codes. It compares the differences between the 2000 model year Accent and previous evaporative emission systems... Que puede ser? Tiene dos opciones. Primero, puede pagar que un tecnico diaga el problema (exactamente) o sigue, secudariamente, su adivnaza.

E4 Outdoor activation of low pressure switch/ less suction pressure.

Check back pressure, which should be 60 PSI when ambient temp 98 degree.If not Short of gas- find leak and arrest. And do gas charging. Even due to indoor coil dust blocked also e4 arise. Clean the coil and reset it.

When the pressure switch fails the comperssor will overpressure to the point of safety release at about 150 - 160 psi. It sounds as if your compressor is not producing enough pressure to cycle off at 120 and just keeps running. This happens when air is leaking from fittings or worn cylinder / reed valves. Don't worry, with some simple tests we will find the actual problem. I am assuming that your compressor is oilfree type. If there are leaks the compressor may not reach set pressure. I use soapy water on all connections and on the head/headvalve (remove plastic covers to get to all parts that may leak) while compressor is running. Make repairs as necessary. If still low pressure, while compressor is running and has reached max obtainable pressure (in your case 60 lbs), carefully place finger over intake port hole (remove filter). If the compressor is pumping normally but leaking there will be ample suction at intake and cause the compressor to speed-up when intake is obstructed with finger. If you feel plenty of suction and no visible (soapy water) leaks, then the problem is probably the cylinder /ring is not correctly seating /scratched and air is leaking past cylinder. Make sure that the cylinder /piston ring is properly aligned and that the lip on the vinyl ring is up toward the head. On oilfree compressors you can examine the cylinder by pushing the piston all the way up, then look for scratches neer top of cylinder. If scratched, pressure is leaking past cylinder, install cylinder kit. If you do not feel suction but rather air blowing out of the intake, (do this test when tank has reached 60 psi) then the problem is the headvalve plate/reed valves are leaking. The reeds must seal perfectly on their seats and not be bent or have obstruction. Replace as necessary. If reeds or headgasket is leaking the discharge air will be very hot. Only one other thing to check and that is the intank check valve. Easy to check. Run compressor till you have about 50+ lbs in the tank then unplug compressor. Carefully loosen the inlet hose at checkvalve and listen for air leaking out of tank. (check valve is the brass valve at tank) If leaking replace checkvalve. Use caution when removing head to try and save the gaskets. If you have oil type pump, and no air leaks (soapy water test) suspect reed valves/valve plate. Good luck on your repair and email if you have other question.

Usually, a leak at the pressure switch unloader valve is caused by the checkvalve in the tank. The unloader valve at the pressure switch bleeds out the air from discharge tube after compressor reaches set pressure. This only takes a few seconds. If air continues to leak then air is leaking back into the discharge tube past the tank checkvalve. Follow the air discharge line from the compressor to the brass valve at the tank. The brass valve is the checkvalve that holds the pressure in the tank. There are usually two connections at this valve. One is the unloader tube to the pressure switch. Simple test for leaking checkvalve, with pressure in tank unplug or switch off the compressor and remove the small unloader line at the checkvalve(brass valve) and look/listen for leak. If leaking, remove the checkvalve and examine seat/check for debris keeping the valve slightly open. If it cannot be cleaned, order generic replacement from www.grainger.com. It will cost less than the factory checkvalve. Just pay attention to the thread sizes for easy fit. Good Luck on your repair and email if you have questions.

I have worked on many makita compressors and have run-across this problem on a few of them. Your compressor has a check valve that is supposed to hold tank pressure after the switch reaches set pressure. There is an unloader valve built into the pressure switch that releases the pressure in the discharge hose after the unit shuts off. The unloader allows the compressor to restart with-out any pressure in the discharge line. If the brass check valve is leaking pressure back into the system, air will leak out of the unloader valve. Follow the discharge line to the tank and you will see the brass check valve. To test valve for fault, run the compressor till it builds around 80 psi and unplug the unit from the wall outlet. Remove the 1/4" hose connector from the check valve and check for air leaking out of the valve. If it is leaking you can order form www.toolpartsdirect.com. or call the makita 1-800 number. The price is about the same. Good Luck on your repair.