Problem with O2 sensor
03-06-2004, 03:31 PM
#1
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Location: Long Beach, CA, USA
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Problem with O2 sensor
For some reason my Primary O2 sensor is reading between 2-3 volts when it is idle. Under load the voltage jumps up to 5 volts and fluctuates. My secondary O2 is only reading between 0.1-0.9. In the manual it says that it is supposed to be in between 0.1-0.9. I have a 98 Accord Couple 4 cyl. thanks in advance for the help.
03-06-2004, 03:35 PM
#2
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Re: Problem with O2 sensor (SmallzTek)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SmallzTek »</TD></TR><TR><TD CLASS="quote">For some reason my Primary O2 sensor is reading between 2-3 volts when it is idle. Under load the voltage jumps up to 5 volts and fluctuates. My secondary O2 is only reading between 0.1-0.9. In the manual it says that it is supposed to be in between 0.1-0.9. I have a 98 Accord Couple 4 cyl. thanks in advance for the help.</TD></TR></TABLE>
Sounds like it has an internal short to the heater circuit.
Sounds like it has an internal short to the heater circuit.
03-06-2004, 09:59 PM
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a little O2 basics, voltage is high when mixture is rich, low when lean. hopefully switching rich to lean, 400mV-600mV when warm in closed loop. in open loop it should not be switching, or will not be switching. O2s work relatively similar to batteries, and have a tendancy to fail low. either they fail low or they become lazy and switch slow. a lot of OBD2 systems will not go into closed loop until the O2 sensor confirms a rich condition, which all cold motors should be. so in youre case, you are doing something wrong because you will not have 2-3 volts. O2s work 0-1 volt DC. dont worry about youre downstream O2, it is for the sole purpose of detecting catalyst innefficiency to set a catalyst inefficiency code. it is irrelevant for any drivability issues. my way of testing an oxygen sensor- backprobe the signal wire. very important that you backprobe the signal not something else. precondition the vehicle meaning warm it up, 2000 RPM for 2 minutes. when the PCM goes into closed loop the signal will start switching high to low for the purpose of catalyst efficiency. if it is not switching it may be a bad O2 or a lean/rich condition. most common for a bad 02 would be staying around 100mV or .1 volts DC. snap the throttle and you the voltage should exceed .8v's. snap throttle the injectors should be dumping fuel. if you are not confident in that spray some carb spray down the throttle body and make sure the motor is running rich. if the motor is rich and the voltage is not atleast .8 or 800 mv, you know you have a bad O2. if it excedes .8 and drops back down to a low reading, than most likely the motor is running rich. very rarely will an O2 stick high, but if for some reason you think it is not running rich and the signal is sticking high, put youre hand over the throttle body and that will obstruct air and cause it to lean out. i hope that wasnt too much crap at once, but good luck.
03-07-2004, 04:52 AM
#6
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Re: (SmallzTek)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SmallzTek »</TD></TR><TR><TD CLASS="quote">Does anyone know how I could fix this problem? Is this the O2 or is there something else wrong?</TD></TR></TABLE>
If your wiring is ok, replace the o2 sensor.
If your wiring is ok, replace the o2 sensor.
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03-07-2004, 08:48 AM
#8
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Re: (SmallzTek)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SmallzTek »</TD></TR><TR><TD CLASS="quote">What happens if the motor runs rich? How would I fix that problem?</TD></TR></TABLE>
They may be related.
They may be related.
03-08-2004, 10:16 AM
#11
Honda-Tech Member
Re: (SmallzTek)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SmallzTek »</TD></TR><TR><TD CLASS="quote">bump... I need help on this. thanks</TD></TR></TABLE>
If they look good, check for shorts to ground, check for shorts to power, and check for open wires.
If they look good, check for shorts to ground, check for shorts to power, and check for open wires.
03-08-2004, 10:22 AM
#13
Honda-Tech Member
Re: (SmallzTek)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SmallzTek »</TD></TR><TR><TD CLASS="quote">How would I go about doing that? I am a total noob and don't really know how to check for shorts or open wires.
</TD></TR></TABLE>
If no ones been in there screwing with your wiring, i'd just give it a visual check for anything munched up.
</TD></TR></TABLE>
If no ones been in there screwing with your wiring, i'd just give it a visual check for anything munched up.
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