Looking for a little help from the community. I am getting P0136 and P0141 errors on my post-cat O2 sensor and could use some data from your O2 sensor. (I have already looked up the codes and that doesn't mean that the sensor is bad, just not reporting correctly). If anyone has a graphing OBD II scanner or a app like Torque or maybe even Dash Command I would like to see what voltage responses you are getting for O2 bank 1 sensor 2. From everything I can find online you should see a heartbeat style fluctuation that drops below 0.4 and rises above 0.7 volts. It should show approximately equal numbers of up and down cycles. The reason I ask is that mine is reporting a flat line response of steady voltage. More than likely it is toast or a wire got damaged when I replaced the Cat with a catless DP. (I know, I know. Catless DP = O2 errors). That said the DP I purchased included a O2 adapter to keep the sensor from coding. The vendor has been very supportive but they stand by their product not being the cause. So, I just want to see what kind of voltage you are getting on your sensor before I throw another one at the problem. If you have a few minutes just hook up the scanner and test it at idle or rev up to 2-3k rpms and see if it is responding as described above. There are loads of threads about downpipes causes O2 codes. This may be the case here which means a new O2 sensor will not correct and I may have bought a bag of magic beans......... Thanks in advance.
Hi, You are correct the bank one sensor two voltage does fluctuate from 0 volts when you let off the gas up to about .895 volts if lead footing it. At a steady 2000 to 2500 rpm at highway speeds holding a constant speed you should see a figure very close to .7 volts. It will fluctuate a little as about every 5 minutes or so the ECU will temporarily richen the mixture to test the response of the O2 sensor. At these times you will read .855 volts or so with it quickly dropping back down in just a few seconds.
Forgot to add a couple of other thoughts. The steady state driving I mentioned above, that is when the O2 sensor is operating in closed loop and the ECU monitors levels. When your driving it like ya stole it the system goes into open loop mood as its impossible for the ECU to monitor cat efficiency with load varying up and down. If my memory serves right the P0136 is because the spacer removes flow from the O2 sensor and it doesn't respond quickly enough to the tests I mentioned. The P0141 is because with the O2 sensor is spaced out so it gets below 600 degrees and the heater circuit has to come on again. This can eventually burn out the heater element.
Not sure if they do or not. I use DashCommand with an iPhone and wifi OBD adapter. It will specifically measure post cat O2 sensor. The PID to monitor is Voltage Bank 1 Sensor 2 under O2 PIDs when Data Logging.