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Car Forum / Toyota / Toyota Cars / July 2007O2 Sensor Problem Again
I had previously posted about the code P0141 with the O2 Sensor (the post-converter one) in my 97 Geo Prizm. You can see the posts here: http://groups.google.com/group/alt.autos.toyota/browse_thread/thread/27687eef2ae d86b2/479834969c118a57 I ended up returning the universal part and getting the OEM one (it was definitely worth the extra $50), but now the problem is that I cleared the code and it came back after driving for about 20 minutes. I checked the output voltage from the O2 Sensor and it was around 40-50 mV after the car had been running for about 10 minutes (the manual said that it should be between 100 and 900 mV). I then tried giving it a little gas and letting it idle just above 1500 RPMs and the output was jumping around like crazy (the manual says that the output should not change actively and should be fairly constant between 100 and 900 mVs). Does anyone have any ideas of what could be wrong? Is the catalytic converter messed up? Thanks, Dave Sorry for the double post, but I forgot to mention that I also checked the input voltage (it was correct), and the resistance of the heater circuit and it was 10.2 Ohms (the manual said that it should be between 11 and 17 Ohms, but I assume that that was close enough). Thanks again, Dave On Jun 29, 11:29 am, "davejohan...@gmail.com" <davejohan...@gmail.com> wrote: > I had previously posted about the code P0141 with the O2 Sensor (the > post-converter one) in my 97 Geo Prizm. You can see the posts here:http://groups.google.com/group/alt.autos.toyota/browse_thread/thread/... [quoted text clipped - 14 lines] > Thanks, > Dave >I had previously posted about the code P0141 with the O2 Sensor (the > post-converter one) in my 97 Geo Prizm. You can see the posts here: [quoted text clipped - 15 lines] > Thanks, > Dave Do a google for -> mechanical 02 simulator <- I did that and I don't see how the results related to my problem. Dave > <davejohan...@gmail.com> wrote in message > [quoted text clipped - 21 lines] > > Do a google for -> mechanical 02 simulator <- Oh, I think that you're referring to doing something like this: http://clubhondahawaii.proboards58.com/index.cgi?board=diygarage&action=display& thread=1123294890 Is that really a good idea? Dave > <davejohan...@gmail.com> wrote in message > [quoted text clipped - 21 lines] > > Do a google for -> mechanical 02 simulator <- Your cat doesn't really enter into this, Dave. 141 is a trouble code regarding the heater circuit only. As far as output voltage, what you've described is normal. A warm engine running around 2-3k will produce a wave of .1 - .9v cycling 8-10 times per second. But anyway, what do you have on the heater circuit? This is where your problem lies. When you used that aftermarket sensor did you modify the factory harness in any way? I just bought a Bosch OEM sensor, took it out of the box, and then screwed it directly into the same place that the old one was. It didn't say anything about doing anything different than that in the Haynes manual or with the instructions for the sensor, but is there something special that I am supposed to do? Dave > Your cat doesn't really enter into this, Dave. 141 is a trouble code > regarding the heater circuit only. As far as output voltage, what you've [quoted text clipped - 3 lines] > problem lies. When you used that aftermarket sensor did you modify the > factory harness in any way? No, nothing special. I just wasn't clear if you messed with the vehicle harness when you had that aftermarket sensor the first time... > I had previously posted about the code P0141 with the O2 Sensor (the > post-converter one) in my 97 Geo Prizm. You can see the posts here: [quoted text clipped - 15 lines] > Thanks, > Dave Try swapping sensors. The sensor after the converter basically monitors the performance of it. Did you check the condition of the front sensor? It needs to be clean with no powdery build up. The way you describe the millivolt reading, you may have a bad connection to the sensor itself, so it sets the code repeatedly. Just a thought. >> I had previously posted about the code P0141 with the O2 Sensor (the >> post-converter one) in my 97 Geo Prizm. You can see the posts here: [quoted text clipped - 21 lines] > millivolt reading, you may have a bad connection to the sensor itself, so > it sets the code repeatedly. Just a thought. HIS TROUBLE IS NOT THE SENSOR, the sensor has a built-in heater that is on the fritz. The trouble code is that the heater is not working. >>> I had previously posted about the code P0141 with the O2 Sensor (the >>> post-converter one) in my 97 Geo Prizm. You can see the posts here: [quoted text clipped - 24 lines] > HIS TROUBLE IS NOT THE SENSOR, the sensor has a built-in heater that is > on the fritz. The trouble code is that the heater is not working. Sorry Jeff, I did not remember the OP. I think that the lambda sensor will need to be replaced though. > >> davejohan...@gmail.com wrote: > >>> I had previously posted about the code P0141 with the O2 Sensor (the [quoted text clipped - 28 lines] > Sorry Jeff, I did not remember the OP. I think that the lambda sensor > will need to be replaced though. What is the lambda sensor? And how do I check if it's bad and replace it? Dave >> >> davejohan...@gmail.com wrote: >> >>> I had previously posted about the code P0141 with the O2 Sensor (the [quoted text clipped - 32 lines] > it? > Dave A "lambda sensor" is what an O2 sensor is called in Europe.  SignatureRay O (correct punctuation to reply) Thanks everyone for all of the responses and here's my answer to each of your questions/comments: Ph@boy said "Try swapping sensors": I can't swap the sensors, because the connectors are different, but I did the same test that I described previously on the pre-cat sensor and it checked out just fine. High Tech Misfit said "Bosch OEM... that is an oxymoron": I realize that it's a semi-misuse of the term, but I was just trying to refer to the fact that it's not a "universal" O2 Sensor that requires splicing the connector. Jeff Strickland said "Your trouble is NOT the output of the sensor, it's the sensor's 'pre-heater'": So does that mean that the O2 Sensor that I got is defective? Basically, what do I need to do to fix the problem? Also, on a side note, the Haynes manual says that the code P0141 is set when the O2 Sensor reaches 600 degrees (or has run at least 2 minutes) and is not outputting 0.7 Volts. Everyone, thanks again for all of the help, Dave > davejohan...@gmail.com wrote: > > I had previously posted about the code P0141 with the O2 Sensor (the [quoted text clipped - 22 lines] > millivolt reading, you may have a bad connection to the sensor itself, > so it sets the code repeatedly. Just a thought. > High Tech Misfit said "Bosch OEM... that is an oxymoron": > I realize that it's a semi-misuse of the term, but I was just trying > to refer to the fact that it's not a "universal" O2 Sensor that > requires splicing the connector. I understand what you're saying. But Bosch parts, universal or quasi-OEM, typically do not work well in Toyotas. I'm not sure who makes real OEM O2 sensors for Toyotas, NipponDenso perhaps? > Thanks everyone for all of the responses and here's my answer to each > of your questions/comments: [quoted text clipped - 3 lines] > did the same test that I described previously on the pre-cat sensor > and it checked out just fine. The sensors (Bank 1 Sensor 1, and Bank 1 Sensor 2) do different jobs, and they can not be swapped. You could swap the sensors in the case of Bank 1 Sensor 1 and Bank 2 Sensor 1 becasue the Bank 1 and Bank 2 (Sensor 1) do the same job on different banks of cylinders, but Sensor 1 and Sensor 2 are in different parts of the exhaust system (before or after the CAT), and do different things. > High Tech Misfit said "Bosch OEM... that is an oxymoron": > I realize that it's a semi-misuse of the term, but I was just trying [quoted text clipped - 9 lines] > set when the O2 Sensor reaches 600 degrees (or has run at least 2 > minutes) and is not outputting 0.7 Volts. I don't know what the resistance spec is for the heater element, but your heater is not working. Logic says the heater should be essentially a short, there will be some resistance, but the number will be low -- the range of an ohm or two -- not high. The Haynes manual says that the after a time or a temp, the output should be X. My guess is that the time period is elapsing, and if I am right then the heater will not reach 600. I suppose you could measure the output for 0.7 after 2 minutes, or even longer. I do not suppose the sensor will attain 600 in only 2 minutes unless it has a heater. If the output is able to get to 0.7 after any amount of time, then you can be pretty sure the sensor is working, but you still will be facing a broken heater and the sensor will need to be replaced again if that is true. You could check the heater circuit to see if it is even getting power. I suspect the circuit works or the fault code should be different -- I'd expect a code for circuit integrity, and another for component function, but I'm not up on all of the codes and do not know for certain that there are two different codes ... Personally, I'm surprised that the Bosch part has failed. I've used them in several applications on my own fleet of cars and trucks, and have always been satisfied with them. > Everyone, thanks again for all of the help, > Dave [quoted text clipped - 25 lines] >> millivolt reading, you may have a bad connection to the sensor itself, >> so it sets the code repeatedly. Just a thought. The Haynes manual said that the resistance of the heater circuit should be between 11 and 17 Ohms, and the resistance on the one I just installed was 10.2. Also, when I gave it a little gas and held it just above 1500 RPMS the output voltage was jumping around a lot (seemed to be between .2 V and 1.5 V but it was really hard to tell). Earlier qslim siad that that was just the normal wave type of output, but it shouldn't be over 0.9 V. So does it look like the most likely solution is just that part is bad and I need to get another one? Dave > <davejohan...@gmail.com> wrote in message > [quoted text clipped - 82 lines] > >> millivolt reading, you may have a bad connection to the sensor itself, > >> so it sets the code repeatedly. Just a thought. It is sounding like you need a sensor no matter what. If the meaning of P0141 is that the output is not .07 after time has passed or temp has been achieved, then the sensor is the cause. If the trouble is the heater within the sensor, or the sensor itself, I'm not sure it matters. It appears that if the reading is not achieved then the default failure report is that the heater is not working. It follows that if the output is eventually attained, then the sensor is doing what it is supposed to do, but it is not doing it fast enough. You could drive the car until Ray gets back from vacation, he is the guy tat knows the most about this sort of stuff. But, I think the bottom line is that you will be replacing the sensor again. > The Haynes manual said that the resistance of the heater circuit > should be between 11 and 17 Ohms, and the resistance on the one I just [quoted text clipped - 109 lines] >> >> millivolt reading, you may have a bad connection to the sensor itself, >> >> so it sets the code repeatedly. Just a thought. For the sake of accuracy, I misspoke about that wave form. I forgot that we were dealing with the rear sensor. Your manual is correct, the wave form behind the cat should be fairly flat when the engine is warm and revving, and the front sensor is the one that should follow the .2 -.9v pattern. The computer looks at the rear sensor solely for the purpose of proper cat operation. Your trouble is NOT the output of the sensor, it's the sensor's "pre-heater". The sensor is unstable while cold, but the engine needs to run well anyway. So, they designed in a heater circuit to heat the sensor so that it works well even before the motor comes up to temp. Without getting bogged down in really accurate detail, think of the glo-plugs in a diesel engine; they come on so one can start the motor, but when the motor begins running, the glo-plugs are turned off and the motor runs on its own. The O2 Sensor has a glo-plug (of sorts) that helps the sensor function within a narrow range much earlier than without the heater. Your code says the heater is not working right. I like this link for OBD II Codes http://autorepair.about.com/od/obdcodedatabase/a/OBD_1996_year.htm >I had previously posted about the code P0141 with the O2 Sensor (the > post-converter one) in my 97 Geo Prizm. You can see the posts here: [quoted text clipped - 15 lines] > Thanks, > Dave >I had previously posted about the code P0141 with the O2 Sensor (the > post-converter one) in my 97 Geo Prizm. You can see the posts here: [quoted text clipped - 15 lines] > Thanks, > Dave I think the catalytic converter is not working properly and you have a problem with the O2 sensor heater circuit. SignatureRay O (correct punctuation to reply) Is there some way that I can test if the catalytic converter really is bad before changing it? The O2 Sensor is under warranty so I could get a new one for free and try replacing it, but it just seems unlikely to me that the brand new one that I just put in would be bad. Dave > <davejohan...@gmail.com> wrote in message > [quoted text clipped - 26 lines] > Ray O > (correct punctuation to reply) I seriously doubt your CAT is toast. I so doubt it is toast that I would not even consider it as a usual suspect. > Is there some way that I can test if the catalytic converter really is > bad before changing it? The O2 Sensor is under warranty so I could get [quoted text clipped - 32 lines] >> Ray O >> (correct punctuation to reply) Me thinks you are correct. The original was most likely not bad either, however. When a microprocessor is forced to operate outside of it design limits, by a problem as simple as a bad sparkplug, over time the sensor can become fouled. The result can lead to a bad sensor code, while to real problem is not discovered. As in your case the sensor will fail again shortly. I would suggest you take the vehicle to a competent tech with the proper equipment to determine what is causing the microprocessor to operate outside of it design limits, and have it corrected mike > Is there some way that I can test if the catalytic converter really is > bad before changing it? The O2 Sensor is under warranty so I could get [quoted text clipped - 32 lines] >> Ray O >> (correct punctuation to reply) > Is there some way that I can test if the catalytic converter really is > bad before changing it? The O2 Sensor is under warranty so I could get > a new one for free and try replacing it, but it just seems unlikely to > me that the brand new one that I just put in would be bad. > Dave The way to check catalytic converter function is with an exhaust gas analyzer. The technician takes an exhaust sample before the converter through the O2 sensor mounting hole and then takes another sample at the tailpipe. What comes out the tailpipe should be cleaner than what passes through the #1 O2 sensor mounting hole. Take the car to a competent technician for diagnosis and repair. I recommend using an OEM catalytic converter replacement if one is needed, and check to see if it is still covered by the emissions warranty. SignatureRay O (correct punctuation to reply) >> <davejohan...@gmail.com> wrote in message >> [quoted text clipped - 26 lines] >> Ray O >> (correct punctuation to reply) |
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