O2 Sensor Code

[BDSDC]

Car is idling poorly, keep getting O2 sensor code, bank 1, sensor 1. Where is the problem and what needs to be done? Thanks!

[SoCal LS-L]

Well.... replace the sensor...... but that probably wont fix the idling issue. Theres a hundred different things that could cause rough idle, a few are: Bad coil, fouled plug, oil leak into coil/plug connection, sticking intake air control valve, dirty MAF sensor, stuck open EGR valve, faulty cam or crank sensor, coolant temp sensor, head gasket leak, vacuum leak, valve deposits, poor quality fuel, etc etc etc.

Open a search and read through the threads for some ideas where to look first...

And download the service manual posted below in my signature, you will need it.

[trophy956]

hi what code number? what year is your car ?

[BDSDC]

Originally Posted by BDSDC

Car is idling poorly, keep getting O2 sensor code, bank 1, sensor 1. Where is the problem and what needs to be done? Thanks!

Thanks...So far I have replaced TBS, fuel filter, cleaned throttle body, all plugs, Cyl. 5 coil wire. If I disconnect battery resetting computer, the car seems to run better until the car is restarted. Idle gets too low after the car warms up. Originally I was getting a Cyl. 5 misfire code, after replacing coil it ran better for approx. 30 miles. Now it is even worse and I'm getting O2 sensor code #120. Not the MAF code. Car is 1996. Thanks again for your help.

[redlightningsvx]

What's your TPS adjusted to?

[BDSDC]

Update: TPS tested at .51. The engine code I get with ruff idle is PO130 bank 1, sensor 1 circuit malfunction. The idle is good when the engine is cold at 1100 to 1200 RPM. When the idle drops, it drops under 500 RPM and Cylinder 5 mis-fires. What is normal warm idle RPM's? Waiting for new Bosch O2 sensors to arrive. Will replacing O2 sensors raise the idle or help the ruff idle?

Thanks for any help...close to insanity and ready to pull the pin...

[NiftySVX]

The computer will likely still throw a code with your new sensors unless they are genuine subaru parts. Misfire diagnosis is super easy with an OBD II car like yours if you have a select monitor if you know what you're doing. I would take your car to a subaru dealer and have them do it, it won't take one of their master techs more than a few minutes of looking at the data to see the cause. I think the oxygen sensor and the rough idle are unrelated. A bad O2 sensor will not cause the fuel trim to go so extreme that the car has poor idle quality, and once the computer sees the code it's going to ignore it anyway. I would guess you have an ignition problem, possibly #5 coil.