i installed my gutted down pipe and 120 miles later the cel came on. i checked it with my friends obd2 and it came up as PO420: Catalyst System Efficiency Below Threshold.

does the car go into some sort of limp mode with a cel on? as in cutting boost or changing any other settings just to be safe? is it ok to drive with it on? if i reset the ecu, it will go back off right? i deleted it oonce with the obd2, but i hate to keep bothering my friend everytime it comes on.

also, are cel fixes good? i was thinking that maybe the ecu changes air/fuel settings according to what the o2 sesor reads, and a cel fix will just trick the ecu into thinking that evrything is normal, so it would no longer make necessary changes right?

-tj

 

The car should not run any differently with the P0420.
Don't bother resetting it until you do a fix, the code will keep coming back every time the ECU does its catalyst efficiency testing.
There are two types of fixes that have been used successfully, the electronic type that connects to the rear 02 wiring and the mechanical type that uses a spark plug anti-fouler adapter to re-mount the sensor slightly out of the direct exhaust stream. There are plenty of threads on both types.
A properly installed fix will not affect how the car runs, the rear 02 is used only for catalyst monitoring while the front 02 is used for A/F control.
One thing to be aware of is that some of the electrical fixes may prevent the OBDII "readiness tests" from completing. If your state currently has or is planning to implement OBDII scanning for their emissions test, this will cause you to fail.

 

Here is one i made

http://gallery.imprezadriver.com/alb..._006.sized.jpg


And after installation

http://gallery.imprezadriver.com/alb...tert.sized.jpg

 

so basically, is that just an extension? if it is, all i would have to do is fabricate a piece that the o2 sensor will plug into and will also thread into the stock o2 sensor hole? how long does it have to be? thanks

-tj

 

Just an extension around 4cm overall lenght, with a very small hole right through.Approx 3mm wide hole all the way and a 12,5mm wide hole approx 20mm deep where you can plug in the sensor.
http://gallery.imprezadriver.com/alb..._003.sized.jpg

The 2 parts before welding them together:
http://gallery.imprezadriver.com/alb..._002.sized.jpg

If you have the light on you have to go to a dealer to have the warning light reset.

The circle is the exhauspipe and Sonde means sensor.
http://gallery.imprezadriver.com/alb..._012.sized.jpg