2011 CHEVY AVEO; P0137 P2270

sorry but please consider this "TYPO FIX" to my original prior post 171105 (YYMMDD) Nov2017 MIL came on ODBwiz shows Code P0138 (NOT P0238 as shown prior) Thanks SteveG722

180620_1020 edt Re02: 2011 CHEVY AVEO; P0137 P2270 more CLUES Used OBDwiz (ps software) strip chart feature to take a "live look" at voltage on S1 & S2. With engine up to temp & at idle, found voltage on S1 oscillating between ~0.1 - ~0.7 but found voltage on S2 voltage was oscillating but the range was only ~0.1 - ~0.14 and the frequency was not aligned with S1. Discover more Fuel Dodge Ram OBD Codes Hard to believe but now seems likely the sensor I installed on 171128 was bad as bought on eBay or went bad by 171217 when P2270 & P0137 codes showed up. If anybody thinks its premature to conclude the S2 is NG, please REPLY with your thinking? Thanks Steve

When looking at live S2 voltage do a couple of quick snap throttles. Voltage should change max/min indicating active sensor and PCM seeing signal. If no change then possible high resistance or open on O2 signal circuit. A code P0137 may mean that one or more of the following has happened: Faulty o2 sensor Exhaust leak near the rear sensor High resistance or open on O2 signal circuit A code p2270 may mean Exhaust leak near O2 sensor Contaminated or failed HO2S2 (Sensor 2) HO2S2 wiring/circuit problem Loose installation of HO2S2 Read more: p0137 Read more: p2270

180620_1745 edt RE04; 2011 CHEVY AVEO; P0137 P2270 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Hi CJ1, just saw your reply & suggestions......thanks for it; meantime, here's some more data and findings from here; Seems some of it addresses some of the "suspects" you mentioned. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% more CLUES SENSORs & VEHICLE SIDE Went to the vehicle; separated connectors to both S1 & S2; took measurements on all. CG=ChassisGround CONNECTOR PIN ID DEFINITIONS (VS=sockets;SS=pins) vehicle side connector sensor side connector S1 VSS1 S1 SSS1 S2 VSS2 S2 SSS2 Top=surface w snaplock Top=surface w snaplock PIN IDs 1 3 3 1 2 4 4 2 measured OHMS IGNITION=OFF SSS1 (in car) 3-4 8 ohms SSS1 (in car) othercombos open SSS2 (in car) 3-4 6-7 ohms SSS2 (in car) othercombos open SSS2 (out 171128) 3-4 9-10 ohms SSS2 (out 171128) othercombos open measured OHMS IGNITION=OFF VSS1 CG-1 open VSS1 CG-2 0 ohms VSS1 CG-3 10-12 ohms VSS1 CG-4 10-12 ohms measured OHMS IGNITION=OFF VSS2 CG-1 open VSS2 CG-2 0 ohms VSS2 CG-3 10-12 ohms VSS2 CG-4 10-12 ohms measured VOLTAGE IGNITION=ON VSS1 CG-1 0.5vdc VSS1 CG-2 0vdc VSS1 CG-3 12vdc VSS1 CG-4 4vdc measured VOLTAGE IGNITION=ON VSS2 CG-1 0.5vdc VSS2 CG-2 0vdc VSS2 CG-3 12vdc VSS2 CG-4 4vdc SEEMs that data suggests Sensor Heater Resistance data (pins 3-4) on all three sensors looks good (6-10 ohms) Voltage supplied to both S1 & S2 (ignition on; engine off) looks good (~12vdc) Ground supplied to both S1 &S2 vs CG (ignition off; engine off) looks good (0 ohms) I have no idea if the voltages (ignition on; engine off) measured from CG to "other VS pins" are as expected or not (I have no specs) but values measured for VSS1 were "same" as for VSS2; My guess is that suggests the values I measured are OK. a) At this point, seems all the data measured with "engine off" looks fine. b) Does that suggest (confirm) both S1 & S2 are OK? c) If so, I still have to chase the STRIP CHART voltage on S2 (engine warm at idle) being "STUCK LOW" ("varying vs time but in 0.05-0.15v range). Per p2270 P2270 O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 2 Potential Causes The causes for this DTC may include: 1) Exhaust leak near O2 sensor 2) Contaminated or failed HO2S2 (Sensor 2) 3) HO2S2 wiring/circuit problem 4) Loose installation of HO2S2 5) Fuel pressure incorrect 6) Faulty fuel injector 7) Engine coolant leak Faulty purge solenoid valve 9) PCM has failed (1); My manual check for exhaust leaks near S2 and found "nothing obvious") (2); ruled out?) (3); ruled out?) (4); My manual check today found S2 to be tight) (5); I have no idea how to check this; engine runs fine; mileage is normal; I sorta doubt it (6); I have no idea how to check this; engine runs fine; mileage is normal; I sorta doubt it (7); No sign of leaks; level is good; doubt it) (8); I have no idea how to check this; engine runs fine; mileage is normal; I sorta doubt it Any suggestions what to check next, why, & how would be most welcome. Thanks Steve

180620_1925 edt RE05; 2011 CHEVY AVEO; P0137 P2270 Hi cj1 et al, Per your suggestion, just reassembled connectors, connected the PC and put ignition ON engine OFF; voltage from both S1 & S2 showed as 1.28v; then started the engine; watched real-time STRIP CHART; early on, S1 looked "normal"; S2 was flat-line; eventually S2 started showing some "life" but back to LOW AVG & RANGE. "Goosing to 3-4kRPM" seemed to affect the waveform a bit but was still LOW AVG & RANGE. btw, forgot to mention prior but OBDwiz shows system has no problem going to closed loop (does that eliminate anything?). Seems frustrating all this PCM data doesn't seem to "point to the most likely ROOT CAUSE"????? Still seeking and would appreciate suggestions to help me figure this out. Thanks All, Steve

Think you have done as much testing as possible. The PCM is seeing a sensor signal variation but sensor is reporting lean even when sent a rich mixture( snap throttle). Since there are no engine lean codes/no exhaust leaks/sensor installed correctly and engine runs normal, suspect the sensor itself. Try rockauto.com for a sensor. "btw, forgot to mention prior but OBDwiz shows system has no problem going to closed loop (does that eliminate anything?)." That would be a function of the S1 which is switching normal.

180620_2100 edt RE07; 2011 CHEVY AVEO; P0137 P2270 Hi cj1 et al, Thanks for your efforts & offerings re interpretation; To be honest with you, after a forced quick learn as to how this system works the level of detail required to translate data to ID ROOT CAUSE PLUS the net of the REPLIES to my query, I've concluded "the system design including diagnostics" is hugely disappointing vs "what could be done for zip in 2018"; My intent is to post back once I get this ID's & resolved; wiil I live that long; LOL] Sometimes, these kinda FORA are more relaxing than TWTR; LOL Thanks All, Be Well, Steve

180621_1730 edt RE08; 2011 CHEVY AVEO; P0137 P2270 Hi cj1 et al, Seeking feedback on my current (potentially flawed) thinking; I'm about to go do a more scientific search for exhaust leaks between S1 & S2 (as that's a commonly listed potential ROOT CAUSE for my symptoms and it makes sense to me given the data I'm seeing). My symptoms include real time voltage (AVG & RANGE) from S1 look fine; those from S2 are LOW (AVG & MAX are below 0.45 volts). Based data I've posted prior, I'm presuming (for now) both S1 & S2 "are good". What I don't understand are all the webpages that suggest potential ROOT CAUSES for P0137, & P2270; include "engine based stuf" like 1>Intake Air System leak (including vacuum leaks) 2>Low Fuel Pressure 3>Defective engine coolant temperature sensor SEEMs to me any/all of those three kind of problems would surely cause ECM to alter inputs to the engine that would change the chemistry of the exhaust from the engine. So, if the engine exhaust was "lean in Oxygen" due to ECM decisions, why would only S2 be sending LOW voltage signals and not also S1 (would be seeing the very same exhaust, no)?? For those reasons, I don't see how any of those three are potential ROOT CAUSES in my situation. What if anything am I missing? Thanks, Steve

180621_1935 edt RE09; 2011 CHEVY AVEO; P0137 P2270 Hi cj1 et al, FINDINGS re my "scientific search for exhaust leaks" Per one method I found & liked; Ran a vacuum cleaner blower output up the tail pipe Sprayed soapy water on areas of concern; looked for bubbling Front of engine "after S1" was covered with sheet metal plate so not much access Underneath sprayed bottom half of CAT to a foot or so beyond S2 DID SEE OBVIOUS BUT HOT HUGE BUBBLING ~2 inches aft of S2 (at front of a ~12 inch long flex section) So now seems I'm stuck wondering IF that is "my ROOT CAUSE" for P0137 P2270??? SEEMs only way to know is "go to a muffler joint" and see if they agree there's "a leak deserving fixing" (at what cost?) I've got a couple PIX but no idea how to post them here. Thoughts welcome. Thanks Steve

Could try exhaust tape to seal leak in order to prove lean S2. Haven't used it myself but something to try.

180621_2010 edt Re10: 2011 CHEVY AVEO; P0137 P2270 Hi cj1, Tape seems like a great idea to "see if it makes the MIL world go away" The joint looks like it might be tough to "seal"; if it seems doable, I'll give it shot; will advise. Thanks Steve

180622_1657 edt Re12: 2011 CHEVY AVEO; P0137 P2270 Hi cj1 et al, FRIDAY's UPDATE Closer visual inspection of the suspected exhaust leak area (just ~2" aft of S2 & just at front joint with I guess its a heat exchanger?; has a flexible woven SS cover) found a "crack" running ~3/4 of the way around ("hard to access" TOP was the worst; murphy's law again). Not an easy place to apply "Exhaust Tape" so opted to go with QUIK SEAL; Thermosteel 2400°F Cold Weld https://shop.advanceautoparts.com/p/car ... cold-weld- 18003tri/7160074-p?c3ch=PLA&c3nid=7160074-P&adtype=pla_with_promotion&gclid=EAIaIQobChMIqqDErcTn2wIVEcZkCh3TiAAGEAQYBCABEgJtQPD_BwE&gclsrc=aw.ds Applied two layers this afternoon; now still "air drying"; instructions say initially let it air cure for ~4hrs min at 80oF; then let it continue air curing to ~24 hrs. Can't wait to "fire up the engine" and see if S2 signal voltage gets back to "normal" (spends some time above 0.45v?); At this point, I'm pretty confident this was my ROOT CAUSE and hope the goop stays in place at least long enough to get some "good data"; we'll see. Will check it out tomorrow (seems will be raining here in RI) and will post back with my results. Thanks, Steve

180626_0945 edt Re13: 2011 CHEVY AVEO; P0137 P2270; UPDATE; WRAPUP Hi cj1 et al, TODAY's UPDATE; WRAPUP >180624_1000; TESTING; Started engine; let it idle to stable temps; OBDwiz strip chart of voltage on HO2B1S2 showed MAX of peaks was now higher than prior but only to ~0.2-0.3v (vs above 0.45v). Soap bubble retest confirmed more leakage still at the front of the "heat exhanger". Bought a 2nd jar of CarGo Thermosteel 18003TRI and patched it up. >180625_1200; TESTING; Soap bubble retest now showed NO bubbles (leakage) at the front of the "heat exhanger"; Started engine; let it idle to stable temps; OBDwiz strip chart of S2 voltage initially showed it to be "pretty flat below 0.45v" but with some goosing, saw some variation with a few peaks above 0.45v. Then went for a ride and still watching strip chart of S2 voltage; while variation was at a much lower & irregular frequency than S1, the chart confirmed S2 voltage DID now occasionally peak up around 0.6-0.7v. At that point I concluded the S2 voltage profile should no longer support the P0137 or P2270 codes. For now I've elected to NOT manually reset the DTCs, Freeze Frame, Test Monitors, etc using the scan tool; Instead I'm going to wait & see if three consecutive "good trips" (three consecutive trips in which the monitor that set the DTC is run and passes) will turn off the MIL (Fortunately, my Inspection sticker is good thru Oct2019!) LESSONS LEARNED; a) The S2 sensor was NOT the cause for the faults found in Jun2018; b) The S2 sensor I replaced in Nov2017 may well have been "good"; c) Not knowing how long my Thermosteel patches will hold up, I am now aware I may soon need to have my front exhaust pipe replaced (ugh; after 7 years & only 41k miles). GM Part No.: 96654193 WALKER 54895 Front Pipe Hope the info in this thread is helpful to somebody down the line. Thanks Be Well Steve

Thanks for the update/results. "Then went for a ride and still watching strip chart of S2 voltage; while variation was at a much lower & irregular frequency than S1, the chart confirmed S2 voltage DID now occasionally peak up around 0.6-0.7v." Note that the after cat o2 sensor normally moves slowly above/below .45v unless there is a an engine acceleration/deceleration. The pre cat to after cat o2 sensor movement is at least 10/1 with a good cat converter.

180626_1330 edt Re15: 2011 CHEVY AVEO; P0137 P2270; UPDATE; WRAPUP Hi cj1, Thanks for sharing your comments based your obvious knowledge/experience here and on the FORUM. Pretty clear you know a lot more than I do re OBDII etc but occasionally we can all still manage to "learn something new from others". Be Well Steve