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Car Forum / Honda Cars / April 2006O2 sensor controversy again
The question of whether an O2 sensor can be bad enough to cause drivability or fuel economy problems without triggering OBDII codes has another data point. In the alt.autos.subaru forum somebody asked for help sorting out very troublesome hesitation after slowing in a 2006 Outback. A respondent had the same problem in his car, and pressured the dealer to do *something*! The dealer replaced the O2 sensor (front one, I presume) in spite of lack of diagnostic codes and the symptom disappeared. Mike > The question of whether an O2 sensor can be bad enough to cause drivability > or fuel economy problems without triggering OBDII codes has another data [quoted text clipped - 7 lines] > > Mike my experience is yes, it can definitely scratch that itch. with cheapo aftermarket sensors, my '89, which has a slight tendency to hesitiation anyway, is /way/ worse. no codes. but when i use a new oem sensor, that problem all but disappears. Am 89 is not OBDII compliant and does not monitor the sensors that close and the sensors are totally different. The OBDII system monitors heater current and voltage and switching times and voltage to very precisely determine what they are doing. The chance of them causing a problem without setting a code is extremely slim. They can be setting sub codes long before turning on the light on the dash. The information in the computer should be thoroughly analyzed as swapping parts is expensive and could just be masking the real problem. >> The question of whether an O2 sensor can be bad enough to cause >> drivability or fuel economy problems without triggering OBDII codes has [quoted text clipped - 11 lines] > anyway, is /way/ worse. no codes. but when i use a new oem sensor, that > problem all but disappears. > Am 89 is not OBDII compliant and does not monitor the sensors that close > and the sensors are totally different. The OBDII system monitors heater [quoted text clipped - 4 lines] > computer should be thoroughly analyzed as swapping parts is expensive and > could just be masking the real problem. I would have thought OBDII would catch O2 weakness, too, but as the Subaru experience illustrates it isn't necessarily so. I am puzzled what sort of out-of-the-box defect the sensor would have that would cause it to behave so badly and not be tattled on, though. Mike > > Am 89 is not OBDII compliant and does not monitor the sensors that close > > and the sensors are totally different. The OBDII system monitors heater [quoted text clipped - 11 lines] > > Mike -------------------------------------- Maybe the out-of-the-box defect was caused by the BOX ITSELF (like it had the word BOSCH on it)? I keep hearing horror stories about BOSCH, and having owned Volvo and VW, I believe it. :-( 'Curly'  SignatureIf there are a couple of _underscores_ hidden in my return address, you'll have to remove them to reply . . . . Thanks. >> > Am 89 is not OBDII compliant and does not monitor the sensors that >> > close and the sensors are totally different. The OBDII system [quoted text clipped - 22 lines] > > 'Curly' Bosch,the new Prince of Darkness? (Lucas being the old one) SignatureJim Yanik jyanik at kua.net > I would have thought OBDII would catch O2 weakness, too, but as the Subaru > experience illustrates it isn't necessarily so. I am puzzled what sort of > out-of-the-box defect the sensor would have that would cause it to behave so > badly and not be tattled on, though. > > Mike =============================== :-) Maybe the out-of-the-box defect was caused by the BOX ITSELF (like it had the word BOSCH on it)? I keep hearing horror stories about BOSCH, and having owned Volvo and VW, I believe it. :-( 'Curly' I won,t believe it until I see it. Of coarse Subaru may have a defect in their OBDII code. Bad enough to cause fuel economy problems you could definitely see on the graph of the sensor. >> Am 89 is not OBDII compliant and does not monitor the sensors that close >> and the sensors are totally different. The OBDII system monitors heater [quoted text clipped - 11 lines] > > Mike > I won,t believe it until I see it. Of coarse Subaru may have a defect > in their OBDII code. Bad enough to cause fuel economy problems you [quoted text clipped - 16 lines] >> >> Mike I did some Googling on "lazy oxygen sensor" and there were quite a number of articles about the O2S affecting fuel economy.(without setting a code) SignatureJim Yanik jyanik at kua.net > Am 89 is not OBDII compliant and does not monitor the sensors that close and > the sensors are totally different. The OBDII system monitors heater current > and voltage and switching times and voltage to very precisely determine what > they are doing. monitoring heater current allows determination of element temperature if taken to it's logical limit and simple burn-out at its most basic. other than that, unless it's truly sophisticated, which i doubt in a very noisy electrical environment like under the hood of a car, diagnostics are going to be fairly basic stuff. the primary fault detection mode afaik is to set differential limits between primary and secondary sensors, and trigger if exceeded. > The chance of them causing a problem without setting a code > is extremely slim. They can be setting sub codes long before turning on the > light on the dash. The information in the computer should be thoroughly > analyzed as swapping parts is expensive and could just be masking the real > problem. but most people take it to a shop that has testing tools. the obdc computer therefore doesn't need to be that sophisticated. for the home mechanic, and in the absence of these expensive diagnostics, a few parts scavenged from a junk yard, which is where i got the sensors for my comparisons, can be a /much/ cheaper way of determining the level of problem. >>>The question of whether an O2 sensor can be bad enough to cause >>>drivability or fuel economy problems without triggering OBDII codes has [quoted text clipped - 12 lines] >>anyway, is /way/ worse. no codes. but when i use a new oem sensor, that >>problem all but disappears. |
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