Like was said before... get a cheap O2 sensor to plug the second hole in your exhaust, pull your second O2 sensor out [still connected] and tie it up out of the way so all it'll ever read is fresh air. That should be plenty to trick your ECU into thinking all is well.

Or, you could put in a high flow cat and your ECU will read all is well as well.

Or, you could buy a little trick box that will do the same thing as the first method.

I believe that makes three methods to deal with your situation...

 

i removed my cat and my car runs better in the higher rpms when the check engine light is on

 

The O2 sensor, is essentially a pressure sensor. It senses the pressure of the unburnt oxygen, yes.

I thought only the wideband units were heated, maybe the 4-wire, in his car is also... dunno.

-PHiZ

 

In 4 wire sensors there are two ground wires to get more accurate readings than the old single wire standard, the other two wires are signal and heater power. This arrangement also helps make more accurate readings because the old single wire sensors could only get a decent reading above a certain temperature, which meant it had to happen above idle. The heated O2 sensors see much less fluctuation, and thus are more stable for the ECU to use for tuning. This is especially true on engines like the WRX, which has a fuzzy logic system to optimize the fuel and spark patterns based on how the car is driven.

A true "wide band" O2 sensor isn't much different from the 4 wire sensors, but have a 5th wire that I forget the purpose of at the moment. Wide band O2 sensors are more adept at measuring the presence of other gases in the exhaust though than production O2's.

 

maybe my sensor after the cat isn't the problem?? when i got the cel it said o2 heated sensor malfunction. is that the one after the cat?? or one of the ones before it??

 

http://www.londonautoclub.org/html/T..._CEL_Codes.htm

-PHiZ

 

A fouled O2 sensor can/will show a fault as well. In twin sensor setups, the forward sensor usually sees hot enough exhaust gas to stay clean, and the rear one usually sees enough heat to stay clean since it's immediately after the cat, or inside it. Since you don't have a cat anymore, it is possible that the engine is running rich, which makes the exhaust colder than it ordinarily would be, and could be cold enough to allow carbon fouling by the time the exhaust reaches the second O2 sensor.

First things first, let's stop with the "what ifs", grab a wrench and take a look at your O2 sensors. They should be a whiteish tan color if they're doing fine, otherwise, there's a strong chance it's fouled and causing your fault. If that is the case, try one of the three methods I offered earlier to prevent the second sensor from fouling, which will also take that CEL off your dash.

 

i checked the second sensor and it looks dark i havent seen the first one yet. i also unplugged the second one and plugged the hole in the exhaust and the cel keeps coming up

 

Well, a fouled O2 is dead and doesn't matter what you do to it after it becomes fouled.

Time to whip out a wiring diagram and start verifying continuity on the O2 sensor wires as well.

 

if i get a obd 2 obd1 conv. will that solve the problem???