I changed my o2 sensor today. I bought a universal one from Bosch and soldered the old plug on. The fault light went away. Before I changed it the car ran fine. Just had the cel. Now that I have changed it, the car has a rough idle. It's like it's trying to idle to low. I let it sit and idle for 10 minutes in the hope that the computer would adjust. No help. I drove it for about 10 miles. No help. I let it idle some more but it is still rough. Any ideas?

I will be changing my o2 sensor as soon as it gets here. I purchased a new OEM style o2 off ebay for $60.00 I just plug it in and go. Reset the CEL (pull the #14 fuse for a few hours) to clear all codes, then if this does not help I would simply turn the idle up a tad. Bang on your cat and see if it is a little clogged.

I changed my o2 sensor today. I bought a universal one from Bosch and soldered the old plug on. The fault light went away. Before I changed it the car ran fine. Just had the cel. Now that I have changed it, the car has a rough idle. It's like it's trying to idle to low. I let it sit and idle for 10 minutes in the hope that the computer would adjust. No help. I drove it for about 10 miles. No help. I let it idle some more but it is still rough. Any ideas?

 

Take it out and drive it hard on the hwy and hopefully the heat will burn things off in there. I just changed mine and my Sub noe idles a lot better than it did. Are you sure you got the right one? Are all your connections good?

Well the idle problem got better after I drove it to work the next day, but the CEL came back. I guess the o2 sensor was not bad. I paid a garage to check it out before I changed the sensor. He said it was definitely the front o2 sensor. He wants me to bring it back to him. I had Advance pull the code after this second time and it is still the same "Fuel Trim Malfunction Bank 1" failure. I replaced the fuel filter and checked the plugs. Car runs good. Just has the CEL.

Any ideas?

What Year model? '99-'00 Forester / Impreza? '99 Legacy?

There was a recall on MAF sensors. They would flag that code.

95 Legacy L

I changed my o2 sensor today. I bought a universal one from Bosch and soldered the old plug on. The fault light went away. Before I changed it the car ran fine. Just had the cel. Now that I have changed it, the car has a rough idle. It's like it's trying to idle to low. I let it sit and idle for 10 minutes in the hope that the computer would adjust. No help. I drove it for about 10 miles. No help. I let it idle some more but it is still rough. Any ideas?

If you bought the universal OS2, be very careful when doing the wire. The color doesn't necessary match (white to white, black to black, brown to brown) with that of your Subie's. When I did mine, I didn't match the color, instead, I read very carefully what each wire's signal is and did it accordingly when attaching/connecting the wires. It's not hard but tricky, so make sure to read carefully what each wire's signal is. Strip them and connect each correctly and you should be okay. I think your rough idling may be a incorrect wiring you did.

To reset my CEL I was told to disconnect the battery for 10 minutes or so, reconnect it, then start the car without touching the gas pedal at all. Then let it idle for 5 - 10 minutes. This has worked for me when the CEL has come on.

 

 

I changed my o2 sensor today. I bought a universal one from Bosch and soldered the old plug on. The fault light went away. Before I changed it the car ran fine. Just had the cel. Now that I have changed it, the car has a rough idle. It's like it's trying to idle to low. I let it sit and idle for 10 minutes in the hope that the computer would adjust. No help. I drove it for about 10 miles. No help. I let it idle some more but it is still rough. Any ideas?