P0141 still being set
in [Toyota]
|
Prev: A40D rebuild question
Next: repair ripoff?
From: johngdole on 4 Sep 2007 22:55 This may indicate that the previous mechanic tried to fix a grounding problem for the Heater Return (for the lack of a better term) wire from the sensor. Which means the transistor in the ECU may be bad and not dropping the heater return line to ground when the ignition is turned ON. So the previous mechanic splices the return wire directly to ground, hoping to solve the problem which he obviously didn't do. That's why you see a splice from the return directly to ground -- it's a futile attempt to bypass that grounding transistor "switch" that turns on the heater in the ECU. So do this check: Since you already checked and had battery voltage at the Heater Battery + wire, you need to check the Heater Return wire and make sure it goes to ground and therefore completes the circuit that turns on the heater. So at the oxygen sensor's connector towards the ECU, and with the ignition switch to ON, check the continuity of the Heater Return wire to Ground. Do you see continuity to Ground? (Be careful not to connect the ohmmeter to battery voltage wire or you'll fry the meter). www.pickapart.com may be a good way to get a half way decent ECU. Please keep us posted. On Sep 4, 12:28 pm, "davejohan...(a)gmail.com" <davejohan...(a)gmail.com> wrote: > I then noticed that up near > the console this output wire had been spliced, so I opened up the > console to investigate. I then noticed that the wire had been split > with one of the wires going to the PCM and one being grounded to the > metal of the console. I believe that the wiring had a problem and they > had tried to re-run the wire themselves and had grounded it for some > odd reason (the wire was blue and black so maybe they thought the > black meant that it was supposed to be grounded or something). But I > removed this wiring and re-ran the wire like they should have. I > tested the connection between terminal 19 on the PCM and the output of > the O2 Sensor and it passed, so I assumed it would work and put > everything back (dumb, I know). But then the code came on almost > instantly after I turned the car on (more like what I expected). When > I spoke with the teacher in the auto shop, he said that being grounded > like that might have messed up the O2 Sensor and that I should redo > the diagnostic checks to make sure that it was still OK, because it > was very unlikely that the PCM was bad (just like Ray O said), so I'll > redo that check and hopefully it will just be something simple like > getting a replacement O2 sensor and swapping it out. > > And just for completeness, here's the test that I did: > 1) Disconnect the O2 Sensor and ensure that there's 12 V at the Black/ > Red wire coming from the car with the ignition on. > 2) Reconnect the O2 Sensor and ensure that there's 10 V at the Blue/ > Black wire coming from the O2 sensor with the ignition on > 3) Disconnect the O2 Sensor and ensure that there's 11.7-14.3 Ohms > between those same terminals on the O2 Sensor at 68 degrees F. > 4) Ensure that the output of the O2 Sensor is holding steady between > 100 and 900 mV after reaching standard operating conditoin. > > Thanks for all the help and I'll let you know what I find out. > Dave
From: johngdole on 4 Sep 2007 23:02 Stay with Bosch for now. IMO they are the best-in-class sensors, particularly the planar type. I think the problem is the ECU transistor that turns on the heater, therefore you saw the futile attempt to bypass it by the splice directly to ground. http://www.boschautoparts.com/Products/OxygenSensors/PlanarO2 Beck Arnley is a re-box company. Don't know who's sensor you get at any given time. It may change. I would personally stay away from the Denso junk. On Sep 4, 4:58 pm, "davejohan...(a)gmail.com" <davejohan...(a)gmail.com> wrote: > The O2 Sensor that I currently have is a Bosch and here's the link to > it on AutoZone's website:http://www.autozone.com/selectedZip,85743/initialAction,partProductDe... > > I also noticed that Autozone has some other brands available: > Beck Arnley -http://www.autozone.com/R,APP242730/vehicleId,2341202/initialAction,p... > Denso -http://www.autozone.com/R,APP249492/vehicleId,2341202/initialAction,p... > > Should I try getting one from a different brand? Or is the Bosch one > just fine? > > Thanks again for all the help, > Dave
From: Jeff Strickland on 4 Sep 2007 23:03 <davejohansen(a)gmail.com> wrote in message news:1188950336.207828.49860(a)o80g2000hse.googlegroups.com... > On Sep 4, 4:13 pm, "Jeff Strickland" <cr...(a)verizon.net> wrote: >> "Ray O" <rokigawaATtristarassociatesDOTcom> wrote in message >> >> news:Q9mdneK5np1KLUHbnZ2dnUVZ_vihnZ2d(a)comcast.com... >> >> >> >> >> >> > <davejohan...(a)gmail.com> wrote in message >> >news:1188866256.726022.138320(a)22g2000hsm.googlegroups.com... >> >>I posted a little while ago about my 97 Geo Prizm. You can see the >> >> posts here: >> >>http://groups.google.com/group/alt.autos.toyota/browse_thread/thread/... >> >> > After going back and looking at all of the posts, some posters provided >> > incorrect and/or confusing information, so let's start over again. >> >> >> I finally found out that there was a problem with the wiring and fixed >> >> it. I verified that there is now a connection from the O2 Sensor to >> >> terminal 19 on the 26-pin PCM (or ECU or whatever you want to call it) >> >> connector, but I drove the car around the block and the code got set >> >> again. >> >> >> I re-followed the steps that I used to find the bad wiring and >> >> everything checked out and it says that it's a problem with the PCM. >> >> > How did you check the wiring? Did you do a continuity check between >> > the >> > connector on the O2 sensor ande corresponding pin on the harness side >> > of >> > the PCM connector or did you use another method? >> >> > I >> >> looked through the TSB that are listed here: >> >>http://www.tsb.com/TSB/21/972101fn.html >> >> And I noticed that TSB 02-06-04-039 states a problem with Emissions >> >> and ODB II. Could that be related to my problem? >> >> > I'm not sure how GM comes up with titles to TSB's, but I doubt if the >> > TSB >> > you referenced above is related to your problem. TSB's related to a >> > specific diagnostic trouble code ("DTC") generally list the DTC, and >> > that >> > seems to be the case in the list of TSB's for your car. In other >> > words, I >> > would imagine that the title would reference DTC P0141 in the title. >> >> >> Or does anyone have any ideas of what I should try next? >> >> > I see that you had a Bosch sensor installed and you changed it to an >> > "OEM" >> > one. Exactly what brand of O2 sensor is in the car now and where did >> > you >> > get it? Did you have to do any splicing for any of the sensor swaps? >> >> > Also, what is the physical location of the sensor you have been >> > checking? >> > Are you checking the sensor on the exhaust manifold or the one between >> > the >> > catalytic converter and the tailpipe? >> >> >> If it is a bad PCM, should I just take it to a dealer to get it fixed? >> >> And is something like that covered under warranty (I'm at around 95K >> >> miles and it's 10 years old)? >> >> >> Thanks, >> >> Dave >> >> > Bad PCM's are very rare and should be the last thing that gets changed. >> > Unfortunately, you are probably beyond any emissions warranty so it >> > would >> > be a customer pay situation. I wouldn't have a problem with one from a >> > junk yard since the odds are that it will still be OK. >> >> I did not read all of the misleading and confusing posts on this subject, >> but I agree with what Ray has said here, straight down the line. >> >> P0141 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2) >> >> This is a failure of the heater that resides inside the O2 Sensor that is >> after the CAT. > > The O2 Sensor that I currently have is a Bosch and here's the link to > it on AutoZone's website: > http://www.autozone.com/selectedZip,85743/initialAction,partProductDetail/initialpartType,00117/initialR,APP243760/initialvehicleId,2341202/shopping/selectZip.htm > > I also noticed that Autozone has some other brands available: > Beck Arnley - > http://www.autozone.com/R,APP242730/vehicleId,2341202/initialAction,partProductDetail/store,/partType,00117/shopping/partProductDetail.htm > Denso - > http://www.autozone.com/R,APP249492/vehicleId,2341202/initialAction,partProductDetail/store,/partType,00117/shopping/partProductDetail.htm > > Should I try getting one from a different brand? Or is the Bosch one > just fine? > > Thanks again for all the help, > Dave > My _limited_ experience is that Bosch parts are pretty good. You could have one that is broken, but it's hard to tell from here. One thing I do want to caution you on is that there is a difference in the part of the sensor that senses whatever it is sensing, and the part of the sensor that is really nothing more than a heater. Your particular probnlem set is the heater portion, and my feeling is that you are getting side tracked on other stuff. Back in the olden days, sensors were heated by the hot exhaust gas, and whatever they did while they were heating up was not very reliable in terms of clean air. So, somewhere along the line they figured out that if they put a heating element inside, they could get a reliable reading and stable operation much sooner, and I assume at some point they switch the heater off because the exhaust gas is eventually hot enough to do the job. Your problem set is that the heater is not working, I would expect that the sensor circuit would not be very stable until the sensor actually had several minutes at speed to get hot. By the time you get stable readings, the underside of the car should be hot enough that you would not want to be under it with a volt meter. If the sensor was not performing properly, there would be a code that meant TOO RICH, TOO LEAN, or simply MALFUNCTION. Since you do not have these codes, I would confine the troubleshooting effort to the heater circuit -- the heater in the sensor, and the wires in the car that power the circuit. I agree with ray, the computer itself is normally a very reliable piece of equipment. (You have splices that affect this statement though.) You talked in another post about splices and such, this is a bad sign. Very bad. It is difficult to say with any certainty what your problem might be because somebody mucked up the wires and this can easily cause transient issues that are all buty impossible to sort out. The computer puts a signal/voltage on a wire, and given a known number of connections and the load that _should_ be there, it knows that a particular malfucntion exists because the signal/voltage that comes back is not what is expected. We are sitting out here in cyberspace telling you that the trouble is the heating element in the sensor, but the splices you told us about are a huge Red Flag that virtually anything could be the problem. We assume the wires are all original, but in your case it appears that this is not a valid assumption. You should be able to read the resistance on the heating element -- I don't know the spec, but I'd guess that when cold, it should be low, probably less than about 10 ohms.
From: Ray O on 5 Sep 2007 01:40 <davejohansen(a)gmail.com> wrote in message news:1188934119.248472.315850(a)g4g2000hsf.googlegroups.com... > On Sep 3, 6:11 pm, "Ray O" <rokigawaATtristarassociatesDOTcom> wrote: >> <davejohan...(a)gmail.com> wrote in message >> >> news:1188866256.726022.138320(a)22g2000hsm.googlegroups.com... >> >> >I posted a little while ago about my 97 Geo Prizm. You can see the >> > posts here: >> >http://groups.google.com/group/alt.autos.toyota/browse_thread/thread/... >> >> After going back and looking at all of the posts, some posters provided >> incorrect and/or confusing information, so let's start over again. >> >> > I finally found out that there was a problem with the wiring and fixed >> > it. I verified that there is now a connection from the O2 Sensor to >> > terminal 19 on the 26-pin PCM (or ECU or whatever you want to call it) >> > connector, but I drove the car around the block and the code got set >> > again. >> >> > I re-followed the steps that I used to find the bad wiring and >> > everything checked out and it says that it's a problem with the PCM. >> >> How did you check the wiring? Did you do a continuity check between the >> connector on the O2 sensor ande corresponding pin on the harness side of >> the >> PCM connector or did you use another method? >> >> I >> >> > looked through the TSB that are listed here: >> >http://www.tsb.com/TSB/21/972101fn.html >> > And I noticed that TSB 02-06-04-039 states a problem with Emissions >> > and ODB II. Could that be related to my problem? >> >> I'm not sure how GM comes up with titles to TSB's, but I doubt if the TSB >> you referenced above is related to your problem. TSB's related to a >> specific diagnostic trouble code ("DTC") generally list the DTC, and that >> seems to be the case in the list of TSB's for your car. In other words, >> I >> would imagine that the title would reference DTCP0141in the title. >> >> > Or does anyone have any ideas of what I should try next? >> >> I see that you had a Bosch sensor installed and you changed it to an >> "OEM" >> one. Exactly what brand of O2 sensor is in the car now and where did you >> get it? Did you have to do any splicing for any of the sensor swaps? >> >> Also, what is the physical location of the sensor you have been checking? >> Are you checking the sensor on the exhaust manifold or the one between >> the >> catalytic converter and the tailpipe? >> >> > If it is a bad PCM, should I just take it to a dealer to get it fixed? >> > And is something like that covered under warranty (I'm at around 95K >> > miles and it's 10 years old)? >> >> > Thanks, >> > Dave >> >> Bad PCM's are very rare and should be the last thing that gets changed. >> Unfortunately, you are probably beyond any emissions warranty so it would >> be >> a customer pay situation. I wouldn't have a problem with one from a junk >> yard since the odds are that it will still be OK. >> >> -- >> >> Ray O >> (correct punctuation to reply) > > I spoke with the teacher in the auto shop that my wife works at and it > turns out that that TSB is only for Prizm's manufactured in Canada but > that need to pass US emissions, so it doesn't apply. > > Also, here's the full story since it's probably hard to gather it all > from the randomly spread out posts and I left out some info in my last > post: > I bought the car about a year ago and very shortly after I bought it > the code P0141 came on (described as "Post-convertor O2 Sensor heater > or circuit fault" in the manual). I bought a Universal Bosch O2 Sensor > and installed it. The code came back on after about 30-40 minutes of > driving it (which seemed odd since the manual said that it should come > on within 1-2 minutes). The responses on here stated that it was > probably a problem with the splicing I did or something wrong with the > wiring between the sensor the PCM. I put it off until about a month or > two ago when I traded in the Universal Bosch O2 Sensor for a direct > fit one. Once again, the code came back on after about 30-40 minutes > of driving it. I then did the tests in the Haynes manual that I have > and it said that the O2 Sensor was fine, but I noticed that the output > was going through a sinusoidal type of pattern instead of staying > level like the manual said it should. After some investigation and > phone calls it seemed that the catalytic converter was bad, so on > Friday I finally got that replaced. But like usually after about 30-40 > minutes of driving the code came on again. So I called up the teacher > of the auto shop at my wife's work. He looked up the service for a > P0141 on a 97 Geo Prizm and it was almost identical to the steps in > the manual I had, but had an extra step regarding the expected voltage > of the output (should be 10 V). I did this test and noticed that the > output voltage wasn't even close to this. I then noticed that up near > the console this output wire had been spliced, so I opened up the > console to investigate. I then noticed that the wire had been split > with one of the wires going to the PCM and one being grounded to the > metal of the console. I believe that the wiring had a problem and they > had tried to re-run the wire themselves and had grounded it for some > odd reason (the wire was blue and black so maybe they thought the > black meant that it was supposed to be grounded or something). But I > removed this wiring and re-ran the wire like they should have. I > tested the connection between terminal 19 on the PCM and the output of > the O2 Sensor and it passed, so I assumed it would work and put > everything back (dumb, I know). But then the code came on almost > instantly after I turned the car on (more like what I expected). When > I spoke with the teacher in the auto shop, he said that being grounded > like that might have messed up the O2 Sensor and that I should redo > the diagnostic checks to make sure that it was still OK, because it > was very unlikely that the PCM was bad (just like Ray O said), so I'll > redo that check and hopefully it will just be something simple like > getting a replacement O2 sensor and swapping it out. > > And just for completeness, here's the test that I did: > 1) Disconnect the O2 Sensor and ensure that there's 12 V at the Black/ > Red wire coming from the car with the ignition on. > 2) Reconnect the O2 Sensor and ensure that there's 10 V at the Blue/ > Black wire coming from the O2 sensor with the ignition on > 3) Disconnect the O2 Sensor and ensure that there's 11.7-14.3 Ohms > between those same terminals on the O2 Sensor at 68 degrees F. > 4) Ensure that the output of the O2 Sensor is holding steady between > 100 and 900 mV after reaching standard operating condition. > > Thanks for all the help and I'll let you know what I find out. > Dave > OK, next time you buy an O2 sensor, get a Denso. As johngdole mentioned, Bosch is a very good brand, but they do not always work well in Toyotas, and during my time spent as a district service manager for Toyota fixing cars that dealers had trouble fixing, I've never run across problems with Denso, while I occasionally ran into compatibility problems with Bosch. However, in this case, I suspect that the problem is with the wiring harness between the O2 sensor and the PCM and not with the sensor itself. Jeff Strickland is saying that the O2 sensor heater is bad, but I disagree. It seems unlikely that 2 sensors are bad unless there happens to be a compatibility problem, so I would look elsewhere for the source of the problem. I think some of the information in your Haynes manual is incorrect. DTC P0141 should have 2-trip detection logic, which means that it should take 2 trips for the MIL to illuminate unless there is a short or open in the circuit, in which case the light will come on right away. The grounded wire is a clue that someone who is not as knowledgeable as he or she thought she is worked on the car, and it is never a good idea to cut or modify the wire harness between sensors and the PCM. I would double-check the wire in question by unplugging the harness from the O2 sensor and PCM and check continuity through the wire by using a long jumper wire so your meter leads will reach and also check continuity with ground. If the wire has any continuity with ground, then that is the likely cause of the problem - someone may have grounded the wire in more than one location. Also check the wire harness near the exhaust to make sure the insulation did not get melted or cut. -- Ray O (correct punctuation to reply)
From: High Tech Misfit on 5 Sep 2007 06:13
johngdole(a)hotmail.com wrote: > Stay with Bosch for now. IMO they are the best-in-class sensors, > particularly the planar type. I think the problem is the ECU > transistor that turns on the heater, therefore you saw the futile > attempt to bypass it by the splice directly to ground. > > http://www.boschautoparts.com/Products/OxygenSensors/PlanarO2 > > Beck Arnley is a re-box company. Don't know who's sensor you get at > any given time. It may change. I would personally stay away from the > Denso junk. What the hell is it with you and Bosch? Perhaps you had a bad experience with Denso (a rare "lemon part", so to speak). Overall, Denso has proven to be the better manufacturer of these types of parts. |