P0141 still being set
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From: johngdole on 5 Sep 2007 23:20 Dave is looking at a new sensor. And I'm telling him to hold the horses and diagnose the grounding path through the ECU. It's irresponsible for anyone to suggest purchasing new parts when the diagnosis isn't even complete. Besides, the splice was put in for the old sensor, presumably the OEM Denso. The mechanic who put in the splice obviously knew about the problem in the ECU's ground path. That's why he bypassed it. The splice is a no- no, but at least the mechanic knew what connects to what. Perhaps Ray can enlighten us some more on the transistor switch in the ECU for the heater. He should know. As far as compatibility goes: people don't use Toyota gas, fill their non-Toyota tires with Toyota air or drive on Toyota roads. Ray said no Denso problems? Perhaps he never fixed any of the Toyota TSB #EG014-03? EG014-03 M.I.L. ON DTC P1130, P1135, P1150 OR P1155 - Under certain driving conditions, some 2002 model year Camry vehicels with V6 engines may exhibit a M.I.L. "ON" with one of the following DTCs as a result of an Air Fuel (A/F) Sensor manufacturing and installation issue On Sep 4, 10:40 pm, "Ray O" <rokigawaATtristarassociatesDOTcom> wrote: > 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: Ray O on 6 Sep 2007 00:52 <johngdole(a)hotmail.com> wrote in message news:1189048835.035611.70850(a)w3g2000hsg.googlegroups.com... > Dave is looking at a new sensor. And I'm telling him to hold the > horses and diagnose the grounding path through the ECU. It's > irresponsible for anyone to suggest purchasing new parts when the > diagnosis isn't even complete. Besides, the splice was put in for the > old sensor, presumably the OEM Denso. We agree, although I'm not speculationng on why the splice was put in. > > The mechanic who put in the splice obviously knew about the problem in > the ECU's ground path. That's why he bypassed it. The splice is a no- > no, but at least the mechanic knew what connects to what. Perhaps Ray > can enlighten us some more on the transistor switch in the ECU for the > heater. He should know. As far as I know, none of the wires between the O2 sensor and the ECU should be grounded, and grounding those wires may have damaged the ECU. > > As far as compatibility goes: people don't use Toyota gas, fill their > non-Toyota tires with Toyota air or drive on Toyota roads. Ray said no > Denso problems? Perhaps he never fixed any of the Toyota TSB > #EG014-03? > > EG014-03 M.I.L. ON DTC P1130, P1135, P1150 OR P1155 - Under certain > driving conditions, some 2002 model year Camry vehicels with V6 > engines may exhibit a M.I.L. "ON" with one of the following DTCs as a > result of an Air Fuel (A/F) Sensor manufacturing and installation > issue > That TSB refers to conditions with Camrys, while the OP has a Prism, but I get your point ;-) What I should have said is that I have never run into compatibility problems with Denso, while I have occasionally run into compatibility problems with Bosch. As I said before, Bosch is a good brand and I have seen them work perfectly fine in many cases, but when trying to fix a "problem" car, putting in Denso parts has worked in many cases. I can think of no logical reason why this is the case since the specs on the Bosch replacement parts are at least equal to the Denso parts. -- Ray O (correct punctuation to reply)
From: davejohansen on 6 Sep 2007 13:07 On Sep 5, 9:52 pm, "Ray O" <rokigawaATtristarassociatesDOTcom> wrote: > <johngd...(a)hotmail.com> wrote in message > > news:1189048835.035611.70850(a)w3g2000hsg.googlegroups.com... > > > Dave is looking at a new sensor. And I'm telling him to hold the > > horses and diagnose the grounding path through the ECU. It's > > irresponsible for anyone to suggest purchasing new parts when the > > diagnosis isn't even complete. Besides, the splice was put in for the > > old sensor, presumably the OEM Denso. > > We agree, although I'm not speculationng on why the splice was put in. > > > > > The mechanic who put in the splice obviously knew about the problem in > > the ECU's ground path. That's why he bypassed it. The splice is a no- > > no, but at least the mechanic knew what connects to what. Perhaps Ray > > can enlighten us some more on the transistor switch in the ECU for the > > heater. He should know. > > As far as I know, none of the wires between the O2 sensor and the ECU should > be grounded, and grounding those wires may have damaged the ECU. > The wiring diagram doesn't show any grounding and I can't imagine why something like that would be necessary. I also checked the connection between the O2 Sensor and the terminal on the ECU and it passed, so I think that's fine. > > > > As far as compatibility goes: people don't use Toyota gas, fill their > > non-Toyota tires with Toyota air or drive on Toyota roads. Ray said no > > Denso problems? Perhaps he never fixed any of the Toyota TSB > > #EG014-03? > > > EG014-03 M.I.L. ON DTC P1130, P1135, P1150 OR P1155 - Under certain > > driving conditions, some 2002 model year Camry vehicels with V6 > > engines may exhibit a M.I.L. "ON" with one of the following DTCs as a > > result of an Air Fuel (A/F) Sensor manufacturing and installation > > issue > > That TSB refers to conditions with Camrys, while the OP has a Prism, but I > get your point ;-) What I should have said is that I have never run into > compatibility problems with Denso, while I have occasionally run into > compatibility problems with Bosch. As I said before, Bosch is a good brand > and I have seen them work perfectly fine in many cases, but when trying to > fix a "problem" car, putting in Denso parts has worked in many cases. I can > think of no logical reason why this is the case since the specs on the Bosch > replacement parts are at least equal to the Denso parts. I stopped by AutoZone last night and I checked the resistance of the heater circuit of the direct fit O2 Sensor that they had in stock and it was 9.3 Ohms. The manual says that resistance of the heater circuit in the O2 Sensor should be between 11.7 and 14.3 Ohms at 68 degrees F (the resistance of the one that is current in my car was 9.2 Ohms). I also did the measurements at around 80-90 degrees so that means that the resistance at 68 degrees would be even lower (but it's hard to say by how much). But since they obviously aren't within spec and since Ray O said that he has had problems with Bosch O2 Sensors in Toyotas before, I decided to fork over the extra $20 and try out a Denso O2 Sensor. They had to order but it should get here in Friday and I'm keeping my fingers crossed that I can put it in on Saturday and that this problem will finally be solved. Thanks again for all the help and I'll let everyone know how it turns out. Dave
From: Ray O on 6 Sep 2007 23:45 <davejohansen(a)gmail.com> wrote in message news:1189098428.449882.247160(a)d55g2000hsg.googlegroups.com... > On Sep 5, 9:52 pm, "Ray O" <rokigawaATtristarassociatesDOTcom> wrote: >> <johngd...(a)hotmail.com> wrote in message >> >> news:1189048835.035611.70850(a)w3g2000hsg.googlegroups.com... >> >> > Dave is looking at a new sensor. And I'm telling him to hold the >> > horses and diagnose the grounding path through the ECU. It's >> > irresponsible for anyone to suggest purchasing new parts when the >> > diagnosis isn't even complete. Besides, the splice was put in for the >> > old sensor, presumably the OEM Denso. >> >> We agree, although I'm not speculationng on why the splice was put in. >> >> >> >> > The mechanic who put in the splice obviously knew about the problem in >> > the ECU's ground path. That's why he bypassed it. The splice is a no- >> > no, but at least the mechanic knew what connects to what. Perhaps Ray >> > can enlighten us some more on the transistor switch in the ECU for the >> > heater. He should know. >> >> As far as I know, none of the wires between the O2 sensor and the ECU >> should >> be grounded, and grounding those wires may have damaged the ECU. >> > > The wiring diagram doesn't show any grounding and I can't imagine why > something like that would be necessary. I also checked the connection > between the O2 Sensor and the terminal on the ECU and it passed, so I > think that's fine. > >> >> >> > As far as compatibility goes: people don't use Toyota gas, fill their >> > non-Toyota tires with Toyota air or drive on Toyota roads. Ray said no >> > Denso problems? Perhaps he never fixed any of the Toyota TSB >> > #EG014-03? >> >> > EG014-03 M.I.L. ON DTC P1130, P1135, P1150 OR P1155 - Under certain >> > driving conditions, some 2002 model year Camry vehicels with V6 >> > engines may exhibit a M.I.L. "ON" with one of the following DTCs as a >> > result of an Air Fuel (A/F) Sensor manufacturing and installation >> > issue >> >> That TSB refers to conditions with Camrys, while the OP has a Prism, but >> I >> get your point ;-) What I should have said is that I have never run into >> compatibility problems with Denso, while I have occasionally run into >> compatibility problems with Bosch. As I said before, Bosch is a good >> brand >> and I have seen them work perfectly fine in many cases, but when trying >> to >> fix a "problem" car, putting in Denso parts has worked in many cases. I >> can >> think of no logical reason why this is the case since the specs on the >> Bosch >> replacement parts are at least equal to the Denso parts. > > I stopped by AutoZone last night and I checked the resistance of the > heater circuit of the direct fit O2 Sensor that they had in stock and > it was 9.3 Ohms. The manual says that resistance of the heater circuit > in the O2 Sensor should be between 11.7 and 14.3 Ohms at 68 degrees F > (the resistance of the one that is current in my car was 9.2 Ohms). I > also did the measurements at around 80-90 degrees so that means that > the resistance at 68 degrees would be even lower (but it's hard to say > by how much). But since they obviously aren't within spec and since > Ray O said that he has had problems with Bosch O2 Sensors in Toyotas > before, I decided to fork over the extra $20 and try out a Denso O2 > Sensor. They had to order but it should get here in Friday and I'm > keeping my fingers crossed that I can put it in on Saturday and that > this problem will finally be solved. > > Thanks again for all the help and I'll let everyone know how it turns > out. > Dave > Thanks for the update! -- Ray O (correct punctuation to reply)
From: davejohansen on 8 Sep 2007 19:37
On Sep 4, 7:55 pm, johngd...(a)hotmail.com wrote: > 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). I got the Denso O2 Sensor and it still popped up the code, so I decided to rip everything apart and redo the wiring check. Here's the steps I followed 1) Disconnect the O2 Sensor. Turn ignition on. Check the voltage between ground and the O2 Sensor Terminal 1 (Black/Red wire) and ensure that it's 12 V. RESULT: It read 12.4 V. 2) Turn ignition off. Reconnect the O2 Sensor. Disconnect ECU Connectors. Turn ignition on. Check the voltage between ground and terminal 19 (Blue/Black wire) of the 26-pin ECU connector and ensure that the voltage is at least 10 V. RESULT: It read 12.4 V. 3) Turn ignition off. Disconnect the O2 Sensor. Check the resistance between O2 Sensor Terminal 1 (connects to the Black/Red wire) and O2 Sensor Terminal 2 (Connects to the Blue/Black wire) and ensure that it's between 11.7 and 14.3 Ohms at 68 degrees F. RESULT: The Bosch one is 9 Ohms and the Denso one is 16 Ohms, but I think those are both close enough and that's not the problem. The diagnostics say that if all of these tests pass, then you should change the ECU, but from the comments on here it sounds like that's not likely. I also did the test that John Dole suggested to check for continuity between the pin on the ECU and ground and it didn't pass. I'm not an electrician, so here's what I did and someone can tell me if it was a correct check. I hooked an alligator clip with a long cable to the ground terminal of the battery and connected one probe of the multi- meter to it. I then probed Terminal 19 on the ECU with the other probe and it didn't show a connection (didn't beep and didn't show any resistance). Is that the right way to check for continuity between ground and the ECU? But with all of that info, does anyone have any ideas on what's wrong? I think that the O2 Sensor itself is fine and it looks like the wiring between the O2 Sensor and the ECU is fine, so is it the ECU itself that's bad? Or is there some other wiring that's wrong? And how do I find out what wiring is bad? Thanks again for all of the help, Dave > > www.pickapart.commay 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 |