After my track day on 11/21 my CEL came on and i had Santa Cruz Subaru check it. they did my 15K service and pulled the code. the service manager told me the light was on because my EGT was low due to my aftermarket up-pipe and down-pipe making the airflow too fast. he didnt tell which code number it was. performance of the car hasnt change except there is a rattling noise that sounds like is coming from the area of my turbo/up-pipe/down-pipe. i'm gonna take my care to MPJ or another shop on wednesday. but i am wondering if anyone has an idea about what could have caused this and how it could be fixed?

 

Magic 8-ball sez P0420. 2.2k resistor @ 0.5w across the EGT probe harness will fix this after deleting the code.

jason

 

its not this one (got these from the stickies):

P0545
Exhaust gas temperature sensor circuit low input

instead of:

PO420
Catalyst System Efficiency Below Threshold

 

Is the sensor still connected to the pipe? Are there any broken wires? Is it removed? Cut? Hanging loose somewhere?

jason

 

maybe, that rattling sound is coming from my exhaust, not somewhere in the engine bay

 

Answering the questions might help...

 

yes, the sensor is connected. i pulled the code and it is PO546 and the rattling was a loose EGT bung on my downpipe. the code puller said said its the EGT sensor on the uppipe. MPJ thinks its a bad EGT sensor, so they ordered a new one and now i'll just have to wait and see

P0546
Exhaust gas temperature sensor circuit high input