05LeGacY_GT Posted October 10, 2006 Share Posted October 10, 2006 I have a cobb uppipe with no egt sensor an the 2.2k resistor in the harness, a cobb downpipe with cat and stage 1 AP. after installing the uppipe and down pipe got a cel an blinking cursie light pluged in the AP to check the code an i got : P0031 HO2S Heater Control Circuit Low (Bank 1 Sensor 1). Im not sure which sensor that is...Is the the o2 sensor on the exhaust manifold or somewhere else? Link to comment Share on other sites More sharing options...
sgt Posted October 10, 2006 Share Posted October 10, 2006 Probably the rear o2 sensor(in the downpipe/midpipe) Link to comment Share on other sites More sharing options...
05LeGacY_GT Posted October 10, 2006 Author Share Posted October 10, 2006 not sure if its that its also..P0031 - Front O2 Sensor Heater Control Circuit Low..on the sticky code forum.... Link to comment Share on other sites More sharing options...
sgt Posted October 10, 2006 Share Posted October 10, 2006 Thats probably it then. Sometimes they count from Bank 0 instead of Bank 1. Link to comment Share on other sites More sharing options...
05LeGacY_GT Posted October 10, 2006 Author Share Posted October 10, 2006 If i use the perrin o2 senser simulator that will fix it right? and since the sensor is no good does it matter if i leave it in an use the simulator or should i plug the hold and remove the sensor then wire in the simulator? Link to comment Share on other sites More sharing options...
jsalicru Posted October 16, 2006 Share Posted October 16, 2006 O2 simulators wont fix this CEL... its a front O2 CEL, not a rear. "some say, his arms are made of coiled adamantium fibers. And that he tops his cereal with nuts and bolts. All we know is, he's called the Jose." Link to comment Share on other sites More sharing options...
05LeGacY_GT Posted October 24, 2006 Author Share Posted October 24, 2006 so if i use the perrin o2 sensor simulator on the front o2 sensor its not gunna clear the CEL even if i have all the correct wire colors, the signal, 12 volt and gound? Link to comment Share on other sites More sharing options...
Jon in CT Posted October 25, 2006 Share Posted October 25, 2006 How many times are you going to ask the same uninformed question? Make sure the front A/F sensor is securely connected to the engine bay harness. Its cable is easy to spot on my car because it's the only yellow cable near the top of the passenger-side strut tower. If the connection is good, then one of the sensor's heater wires was probably cut where it exits the sensor during the uppipe install. The only cure for that is to replace the sensor. Link to comment Share on other sites More sharing options...
jazzymt Posted January 30, 2007 Share Posted January 30, 2007 Has anyone gotten any further with this CEL? I am throwing it now - the dealer tech was kind enough to hook it up to their computer and watch the readout while running despite my heavily modified exhaust (headers, up, dp, mid). He says it's functioning, it's just running out of spec.  He thinks the missing factory cats is throwing off the rear O2, which is somehow causing the front O2 to overcompensate it's signal? That doesn't make sense though - then tons of people should be throwing this CEL. What is the heater circuit anyway? It doesn't sound related to the readout of the O2 sensors... [CENTER][URL="http://legacygt.com/forums/showthread.php?t=18504"]Subaru Plug & Play Aux-in Mod[/URL][/CENTER] [CENTER][URL="http://www.jazzyengineering.com"]www.jazzyengineering.com[/URL][/CENTER] Link to comment Share on other sites More sharing options...
Jon in CT Posted January 30, 2007 Share Posted January 30, 2007 Every O2 sensor in a Subaru has an internal heater built into it because the sensor doesn't work unless its temperature is a few hundred degrees. One wire to the heater goes, ultimately, to the battery. The other wire goes to the ECU which controls whether or not its grounded. If the ECU is grounding that wire in order to operate the heater but sees that the voltage on that wire is too low while its being grounded, it throws the P0031 trouble code. This problem cannot have anything to do with cats or rear O2 sensor readings. Either one of the two wires to the sensor heater (or some intervening connector) is bad, or the sensor heater itself is bad. Link to comment Share on other sites More sharing options...
jazzymt Posted May 10, 2007 Share Posted May 10, 2007 Wow - I've been living w/this CEL for a long time. FWIW - I finally went to the dealer and purchased a new front O2 sensor. Charged me $155 for it...probably will not buy any more parts from the stealership, but oh well. Took the old sensor out - wires looked fine, but I put the new one in and so far, no CEL. Problem solved. Also - before I replaced it, I tried just resetting the ECU, but the CEL came back on almost immediately after starting the engine - leading me to believe something was actually broken (cut or shorting out) vs. a "out of spec" reading from the combined O2 sensors (ie. the dealership was full of BS as usual). [CENTER][URL="http://legacygt.com/forums/showthread.php?t=18504"]Subaru Plug & Play Aux-in Mod[/URL][/CENTER] [CENTER][URL="http://www.jazzyengineering.com"]www.jazzyengineering.com[/URL][/CENTER] Link to comment Share on other sites More sharing options...
mickeyd2005 Posted May 10, 2007 Share Posted May 10, 2007 $155? Was that after tax? Subaru MSRP is $139.95 and most online parts dealers are selling it for about $100. Before you replaced it, did you try data logging the AFR, AFR learning, and AFR correction while driving in closed loop? When mccorry's front O2 sensor was acting up, his datalogs showed erratic front O2 sensor readings. Link to comment Share on other sites More sharing options...
jazzymt Posted May 11, 2007 Share Posted May 11, 2007 No tax in Montana. Just the regular old dealership shaft. I guess my impatience & lazyness cost me $50...bummer. No data logging on the O2 sensor, although the stealership did a cursory inspection & said it was reading more or less normally, just lower than it should be...? [CENTER][URL="http://legacygt.com/forums/showthread.php?t=18504"]Subaru Plug & Play Aux-in Mod[/URL][/CENTER] [CENTER][URL="http://www.jazzyengineering.com"]www.jazzyengineering.com[/URL][/CENTER] Link to comment Share on other sites More sharing options...
Infamous1 Posted May 15, 2007 Share Posted May 15, 2007 I had mine replaced under warranty. Link to comment Share on other sites More sharing options...
sofi Posted December 5, 2007 Share Posted December 5, 2007 anyone have the part #? Link to comment Share on other sites More sharing options...
toshiba2.5 Posted December 21, 2007 Share Posted December 21, 2007 ok well i changed the 02 sensor and im still getting p0031 code....whats wrong! Link to comment Share on other sites More sharing options...
toshiba2.5 Posted December 28, 2007 Share Posted December 28, 2007 hello???!!? Link to comment Share on other sites More sharing options...
rony Posted January 30, 2008 Share Posted January 30, 2008 Got this code tonight... Car has been running funky when cruising. Ordering new sensor in the morning. My Car vBGarage Link to comment Share on other sites More sharing options...
rony Posted January 30, 2008 Share Posted January 30, 2008 $129 from local dealer, only $10 more than having it next day aired to me.. My Car vBGarage Link to comment Share on other sites More sharing options...
rony Posted January 31, 2008 Share Posted January 31, 2008 New Front 02 in and working. Car is running better now... A noticeable difference. My Car vBGarage Link to comment Share on other sites More sharing options...
toshiba2.5 Posted January 31, 2008 Share Posted January 31, 2008 great it worked out for you..which one did you buy? Link to comment Share on other sites More sharing options...
rony Posted January 31, 2008 Share Posted January 31, 2008 Front Oxygen Sensor Subaru Part Number: 22641AA32AÂ $129.95 USD My Car vBGarage Link to comment Share on other sites More sharing options...
mickeyd2005 Posted January 31, 2008 Share Posted January 31, 2008 Don't forget to check online dealers like king of parts or subarugenuineparts. They sell it for a lot less than MSRP. Link to comment Share on other sites More sharing options...
rony Posted February 1, 2008 Share Posted February 1, 2008 Correct, but I wanted that day and it only $10 than having it next day aired. So... $10 was worth it to me. My Car vBGarage Link to comment Share on other sites More sharing options...
toshiba2.5 Posted February 1, 2008 Share Posted February 1, 2008 im picking one up tomorrow same price Link to comment Share on other sites More sharing options...
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