[CarMech]

99 forester throwing 3 codes P0420 Cat Eff Below Thresh Bank 1, P0440 EVAP, and P0507 IAC RPM High...

Replaced evap valve and gas filler pipe(Check yours if you haven't most likely caked in mud and rusting behind cover)... P0440 gone and P0420 not back yet
still showing p0507....

Cleaned IAC checked again for vac leaks. Reset code again. Idle still seems rough... waiting for it to come back on....

Any ideas forester community?

 

[dswanson6]

Did you ever figur this out? Have the same problem on 1998 Subaru Forester

 

[ferret]

Let me guess ..... 5 speed ...... Your Neutral switch is BAD and must be replaced.

As you decelerate, in gear, the neutral switch is intermittent and indicates to the ECU that you are in Neutral, so the ECU tries to control the idle. Obviously, it can't so it sets this code.

Neutral Switch