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Car Forum / Honda Cars / August 2007Revisit 90 Accord EX O2 sensor
I still have a Code 41 on my F22A4. Since heater resistance is spec 10-20 ohms, the NGK that came out read 19 ohms, and my current Bosch read 5 ohms, I spliced a 14 ohm 1W resistor into the Bosch. The heater circuit read 19 ohms after the splice. Cleared the ECU via fuse. Radio is reset, so I know I pulled the right fuse. Code 41 comes back. I snagged a new Denso (OEM) O2 sensor off Ebay. Plugged it in (didn't bother to install it). Cleared the ECU via fuse. Code 41 comes back. There is 12 volts at the O2 harness. I'm baffled. I guess all I could really do at this point is an ECU swap? > I still have a Code 41 on my F22A4. > [quoted text clipped - 11 lines] > I'm baffled. I guess all I could really do at this point is an ECU > swap? eh? how is it going to give correct signal if it's not installed??? > eh? how is it going to give correct signal if it's not installed??? Note that the problem I'm trying to eliminate is a Code 41 (Heater circuit malfunction), not a Code 1 (Incorrect oxygen content). Yeah, quick search showed it as sensor fault. But some cars use current draw as a test. You have to find the range it accepts for your year. So if current draw is above or below, the code is set. But if current draw is correct, then it may indeed be the ECU. But codes are not always accurate, so you may have to test coolant temp sensor too. On Aug 20, 10:03 am, "runde...@mail.win.org" <runde...@mail.win.org> wrote: > > eh? how is it going to give correct signal if it's not installed??? > > Note that the problem I'm trying to eliminate is a Code 41 (Heater > circuit malfunction), not a Code 1 (Incorrect oxygen content). On Aug 21, 1:00 am, johngd...@hotmail.com wrote: > Yeah, quick search showed it as sensor fault. > [quoted text clipped - 3 lines] > ECU. But codes are not always accurate, so you may have to test > coolant temp sensor too. Why coolant temp sensor? >From the circuit diagram all I can see that is on the same circuit as the O2 heater is the fuel injectors. Low temp (or faulty sensor) puts the system in open-loop mode. It's recommended to check this with sensor codes. Some cars expect current draw to be 0.3-2.5 amps. Outside then it throws heater circuit code. Don't know about that year of yours. A quick look shows you have to check connection to ground at the sensor connector, and also making sure the proper wire has a path to ground and the other wire doesn't (wiring test at sensor, and between the sensor and ECU). So just strapping the sensor may not provide the "ground" it wanted. Best to refer to the proper manual for that year and model. If wiring checked out it's recommended you swap in a known good ECU and see if the code disappears. On Aug 21, 8:11 am, "runde...@mail.win.org" <runde...@mail.win.org> wrote: > Why coolant temp sensor? > > >From the circuit diagram all I can see that is on the same circuit as > > the O2 heater is the fuel injectors. On Aug 21, 9:41 pm, johngd...@hotmail.com wrote: > Low temp (or faulty sensor) puts the system in open-loop mode. It's > recommended to check this with sensor codes. All I have is the dash code, which is a 41. > Some cars expect current draw to be 0.3-2.5 amps. Okay. that would equate to a range of 4.8 ohms to 40 ohms on the heater circuit. > A quick look shows you have to check connection to ground at the > sensor connector, Something I didn't think to check is the resistance of the ECU side of the circuit... hmm. > and also making sure the proper wire has a path to > ground and the other wire doesn't (wiring test at sensor, and between > the sensor and ECU). None of the wires in the plug show continuity with the threaded part of the sensor. > So just strapping the sensor may not provide the > "ground" it wanted. I don't get it. If anything it doesn't provide the heat it needs to enter closed loop. Whether the sensor is threaded into the pipe or strapped to it should not matter at all, right? > If wiring checked out it's recommended you swap in a known good ECU > and see if the code disappears. Anyone have one to offer? You checked: So you check the resistance of the sensor side (plug lead #3/4), checked no-continuity either of #3/4 to GND on the sensor side, and battery voltage from #4 on ECU side. I didn't read that you checked: Just want to make sure the #3 wire going back to the ECU side isn't grounded to chassis with the ECU disconnected; but #3 is grounded with ECU connected. (This is the heater return from #4 for a later model, F23, so YMMV). If this checks out you should test the ECU. But you'll need to find the correct manual and procedure for the F22. And another ECU, maybe: www.pickapart.com Regarding install: I was just wondering if the heat from the exhaust is needed in addition to the heater is all to go closed-loop. May not matter. Anyone? Was the Bosch you used one of the numbers I listed? Just for my reference only. Thanks. On Aug 22, 7:43 am, "runde...@mail.win.org" <runde...@mail.win.org> wrote: > Something I didn't think to check is the resistance of the ECU side of > the circuit... hmm. [quoted text clipped - 17 lines] > > Anyone have one to offer? > On Aug 21, 9:41 pm, johngd...@hotmail.com wrote: >> Low temp (or faulty sensor) puts the system in open-loop mode. It's [quoted text clipped - 31 lines] > > Anyone have one to offer? the probability of ecu failure is very small. check the feed circuitry - unplug the ecu and check continuity for the whole cable route from the ecu plug to the sensor - then get a sensor from a junkyard and see how you go with that for testing. iirc, there was a prelude guy here a while back with a similar problem that disappeared on fitting the oem sensors - and he'd tried all the alternatives. >> eh? how is it going to give correct signal if it's not installed??? > > Note that the problem I'm trying to eliminate is a Code 41 (Heater > circuit malfunction), not a Code 1 (Incorrect oxygen content). but does it not need to be installed to have all elements earth correctly? > runde...@mail.win.org wrote: > >> eh? how is it going to give correct signal if it's not installed??? [quoted text clipped - 3 lines] > > but does it not need to be installed to have all elements earth correctly? I actually did strap it to the exhaust for that reason (maybe a Code 41 is thrown for other reasons?) But as far as I can tell, if the heater circuit grounds anywhere besides the return wire, it's a fault in the sensor. Re: John's post, does anyone know where I could find those current draw specs? I wouldn't have the first clue where to look. BTW, what other changes were made besides taking out the old sensor that gave you the 41? So the Bosch was still in the pipe? Maybe try removing the resistor you spliced in? (particularly *if* ECU tests current draw) The resistor was 1W. But if the heater operates at 12v and if some can draw 2.5 amps, then you'll have 30W on your hands, am I right? rockauto.com shows: Bosch 15710 w/ OEM plug (looks like a planar type btw, not sure) Bosch 15733 Planar type universal type F22A4 uses: 36531-PT6-A02 On Aug 21, 8:09 am, "runde...@mail.win.org" <runde...@mail.win.org> wrote: > I actually did strap it to the exhaust for that reason (maybe a Code > 41 is thrown for other reasons?) But as far as I can tell, if the [quoted text clipped - 3 lines] > Re: John's post, does anyone know where I could find those current > draw specs? I wouldn't have the first clue where to look. On Aug 22, 12:04 am, johngd...@hotmail.com wrote: > BTW, what other changes were made besides taking out the old sensor > that gave you the 41? None aside from replacing the sensor and trying the resistor splice. > So the Bosch was still in the pipe? Yes. > Maybe try removing the resistor you spliced in? (particularly *if* ECU tests > current draw) It threw the code both with and without the resistor. > The resistor was 1W. But if the heater operates at 12v and if some can draw 2.5 amps, then you'll have 30W on your hands, am I right? Yeah, I screwed up. Even at 19 ohms, that's 7.5W. I'd have to find a power resistor rather than the electronics resistor I used. > rockauto.com shows: > Bosch 15710 w/ OEM plug (looks like a planar type btw, not sure) > Bosch 15733 Planar type universal type > F22A4 uses: 36531-PT6-A02 I don't care about the Bosch that much except as an exercise. I've moved onto the OEM sensor. Why the OEM sensor wouldn't work is a complete mystery to me and what suggests I'm dealing with a bad ECU. You might also consider checking the wiring harness. Check the continuity of the signal wires at the ECU harness by jumpering the sensor signal wires at the sensor connector. You want to use high impedance ohm meter to measure the voltage swings while the engine is running at the ECU harness or the sensor may be damaged. I wouldn't temper with the heater BTW. If you select the correct oxygen sensor, particularly the excellent Bosch Planar type, then it's a matter of Plug-and-Play. I've used many of these planar types, including the "universal" type where you have to splice the old connector back on, and Bosch sensors are excellent. I had to use one of the many types of Bosch "universal" sensors just to find a planar for some cars. Note, use only those "universals" approved in the catalog for your car. I even fixed a P0420 (catalytic converter efficiency below threshold) problem dumping the Denso sensors for Bosch planars. Yeah, it turned out to be crappy oxygen sensors from Denso. No more Denso crap for me. NGK should be OK, I do like their Iridium -IX / -Laser plugs. Great stuff. Best-in-class: Bosch Planar type oxygen sensor http://www.boschautoparts.com/Products/OxygenSensors/PlanarO2.htm On Aug 19, 4:49 pm, "runde...@mail.win.org" <runde...@mail.win.org> wrote: > I still have a Code 41 on my F22A4. > [quoted text clipped - 11 lines] > I'm baffled. I guess all I could really do at this point is an ECU > swap? > You might also consider checking the wiring harness. Check the > continuity of the signal wires at the ECU harness by jumpering the [quoted text clipped - 18 lines] > Best-in-class: Bosch Planar type oxygen sensor > http://www.boschautoparts.com/Products/OxygenSensors/PlanarO2.htm wow, spot the shill! you get paid for that? here's the thing tho buddy, most other posters on this [_honda_] group disagree with you and think bosch sensors are crap. based on bad personal experience, that includes myself. want more bad bosch? their spark plugs. inherited a set of platinums with my crx - lousy. only 2k miles old. slow starting, poor pickup, poor top end. replaced with standard ngk's, and now she purrs like a pussycat. bottom line, bosch suck. > On Aug 19, 4:49 pm, "runde...@mail.win.org" <runde...@mail.win.org> > wrote: [quoted text clipped - 13 lines] >> I'm baffled. I guess all I could really do at this point is an ECU >> swap? Your mileage obviously vary, which is fine. We talk about the good, bad and ugly of cars. I have the exact opposite, good experience with Bosch planar sensors than you. I use exclusively NGK Iridiums, but will lean towards trying Bosch x2 and x4 next time because of positive experiences from some owners and myself with the sensors. Although I must say I had just assumed the Bosch plugs are bad, like most people in this group. There are talks of Japanese cars like NGKs and not Bosch; German cars like Bosch not NGKs, etc. But when a Honda part (Denso sensor, Honda DOT3 brake fluid) didn't work so well in a Honda, then I'd be open to try other options. And I happy to find that Bosch makes excellent oxygen sensors for a variety of cars. > wow, spot the shill! you get paid for that? > [quoted text clipped - 8 lines] > > bottom line, bosch suck. |
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