View Single Post
Old 01-25-2018, 07:36 PM   #10
Scooby Newbie
Member#: 468451
Join Date: May 2017
Default 03 Wrx P0448

Originally Posted by Luxkeiwoker View Post
Ok so I measured the voltage at the ECM on the pin while in test mode (I confirmed it as well with the shop manual and it is indeed Pin 13). The voltage is cycling between 11,3 V (battery voltage) and 0 V. I then measured the voltage with the valve disconnected and nothing changed. Still cycling as it should. So the wirering seems to be OK.

I then hooked up the electrical connectors on the valve to my voltmeter and measured the resistance again. It showed ~ 32 Ohms.

Since I still couldn't hear or feel anything during test mode and the plug connected, I decided to hook up the valve directly to a voltage source (10V) by crocodile clips. When connecting the top pin to + and the lower pin - nothing happend. This seems to be the right polarity since the actual plug delivers the voltage to the pin on the top. I switched the power source on and off serveral times since I thought the the valve may just be stuck and could loosen up by quickly applying voltage and disconnecting it again

Oddly enough when I reversed the polarity I could hear a clicking noise which sounded and felt like a closing or opening relais but not like a mechanical valve.

I re-measured the resistance after that again and the voltmeter showed 4 Ohms and slowly rising.

So now what?

Im curious if you ever found a fix for this code? Ive had the P0448 for awhile now and moved states so I need to fix it in order to pass emissions and im having some difficulty

I connected the 2 test connectors under the driver side and checked the function of the vent valve but couldn't hear or feel anything from it. I then took the connector off the valve and measured at the connector. It was varying between 6.4V - 11.3V so I figured the wiring was good according to what others were saying. I took the vent valve off to test and got 26.4 ohms but when I applied power to it, the valve would still actuate which I thought was weird. I still ordered a new vent valve anyways hoping it would fix the problem.

After installing the new vent valve and double checking the wiring, I cleared the code and test drove it but the engine light returned in 5 miles with the same damn P0448 code. I plugged the test connectors together and double checked the voltage coming out to the vent valve connector and it still tested between 6v and 12v, but when I plugged it back in the new vent valve still had no function at all.

Did I somehow short the new vent valve already or possibly just get a ****ty part?

I decided to check the ECM wiring in my 03 WRX and on connector b134, pin 13 is a light green/red wire. Is this the same as the STI? I tested it with the key on it hit 9V then dropped immediately and stayed at 0.042V. With the test connectors together, it was reading 9v - 0.040v then would hit OL and continue on. Now it had me thinking something was wrong with the wiring or it may be a different pin on the WRX.

I am completely stuck and dont know what to do next! If anyone has any answers I would appreciate it!!
* Registered users of the site do not see these ads.
caw94103 is offline   Reply With Quote