I have a 2005 Outback manual with the EJ25 non turbo.  I changed both steering knuckles for used units and now have an ERSS code come up, and car seems to be in a fail safe mode with both fans coming on all the time.  The reason for the knuckle change was bad ball joint in a rusty knuckle that would not come out.   The ERSS,  stands for Error Speed Sensor.  Must be from one of the abs sensors in the knuckle. My code reader says P0500 but does not tell me which one.  I found the following procedure that says it will unlock more codes that will help tell me which abs sensor is bad.  I followed the procedure to the letter 4 different times and it did not work for me.  If someone can point me in the right direction or have any ideas,  I dont want to start changing parts that may be good. 

 

Starting condition: key off, headlight switch off.

Steps 1 through 7 must be performed within 10 seconds.

1. Turn key to ON position. This is the normal running position, the click just before starting, when all the lights on the dash come on, but before you twist to START. Don't start the engine!

2. Within 3 seconds, turn the headlight switch ON.

3. Press the Trip/Odometer button 4 times.

4. Turn the headlight switch OFF.

5. Press the Trip/Odometer button 4 times.

6. Turn headlight swtich ON.

7. Press Trip/Odometer button 4 times. At this point, the DTC display will begin.

8. Turn headlight switch OFF. Not necessary for the procedure, but your display may be dimmed and hard to read in bright sunlight. Besides, why drain the battery?

The DTCs for each module will display in order: ECM, TCM, ABSCM/VDCCM. Press the Trip/Odometer button to cycle between modules. The FSM states that the display will cycle between modules automatically every three seconds if the button is not pushed, but that did not happen in my car - I had to push the button to cycle the display.

For each module, there are three display states:
- Receiving DTC from module (blinking "P" or "C")
- DTC detected & displayed ("P" or "C" followed by 4 digits)
- No DTC found ("P" or "C" followed by "----"

10 seconds is not a lot of time, you may simply be taking too long to complete the sequence.

I timed it. Under 7 seconds.