legacycentral bbs

Hello everyone.

Here is the issue, my NA 2.2L legacy are now running without the oxygen sensor. Moreover, the up pipe has been modified by previous owner that it doesn't has a port for oxygen sensor anymore. Weird thing is, no engine checking lights. I don't know why. Do your cars will send a code if the oxygen sensor is taken off?

Thus I am trying to drill a hole to the pipe and then weld a nut to the hole, to make it a port.

After some research, I understand that all the oxygen sensor is same inside, a battery utilizing the difference of oxygen concentration. Thus it will read 0.5V while the air/fuel ratio is right. Therefore I think I can get an oxygen sensor for other subaru cars. Now the cheapest one I can get is a denso one, part number is 22641-AA042. That is for 04 impreza.



Will this plan work? any suggestions?

Additional Message, I found some environmental information of Subaru cars from the government catalog. It says that FB20 and FB25 engine are using DENSO #22641 sensor for front cat, DENSO #22690 sensor for after cat. I wonder if EJ will also apply the #22641 sensor too.

I would recommend just getting an exact fit denso or ngk off amazon. I paid 48 for mine and it plugs into the harness perfectly.

You mentioned your NA legacy, do you mean normally aspirated? If so, it doesn't have an up-pipe.

I'll echo Mike's comments about getting a direct fit one for your car. Not all O2 sensors are the same. There are single wire O2 sensors, 3 & 4 wire O2 sensors with heaters in them, and wide band O2 sensors. Most new cars have wide band O2 sensors, while the older cars tended to have 3 or 4 wire O2 sensors.

Legacy777 wrote:You mentioned your NA legacy, do you mean normally aspirated? If so, it doesn't have an up-pipe.

I'll echo Mike's comments about getting a direct fit one for your car. Not all O2 sensors are the same. There are single wire O2 sensors, 3 & 4 wire O2 sensors with heaters in them, and wide band O2 sensors. Most new cars have wide band O2 sensors, while the older cars tended to have 3 or 4 wire O2 sensors.

Sorry I didn't quite understand what's what in exhaust system. It is not up pipe, it should be called exhaust manifold with catalyst converter.

It seems that the NA legacy are using a 3 wire O2 sensor. And I will try to fit it with a 4 wire sensor with an additional ground wire for the heater.

I will try and then feed back.

Yeah, the 4-wire sensors work fine. The sensor & heater ground wires can be combined.