Ever since I switched out my ej25 for an ej22 in my 98 outback My car has been intermittently throwing the 0400 code. So far I have found a bad Backflow transducer but I also notice the egr solenoid only opens for a second on engine start and then closes. The egr valve checks fine and is not that dirty. I just cant get vacuum to it.Off the car the solenoid with 14 volts applied functions fine. With the key on I have battery voltage to the connector for the solenoid but when hooked up there is no voltage across the terrminls at the connector. Obviously a large voltage drop. Anyway should there be constant voltage to the solenoid when the key is on or is it intermittent? The solenoid shows 44 ohms across the terminals supposedly in spec.

nice detective work so far, you're on it.

 

there's a tiny thin, quarter sized filter in line with a vacuum hose on the passengers side. it's $7 from Subaru and can cause EGR codes. it's rare, only heard of it happening one time (new valve, gasket, and solenoid did not fix the EGR code), but for $7 it's worth a shot if everything else spec's out.

 

in the end maybe the EGR valve is bad, wouldn't be the first auto part within spec's that causes issues. XT6 throttle position sensors can never be within the spec's outlined in the FSM - so spec's aren't "perfect"

 

did you replace the transducer and how did you know it was bad?

 

curious since that's an odd failure.