O2 sensor problems 2000 Accord SE ULEV

I am trying to solve an oxygen sensor problem with my 2000 Honda Accord
with a 2.3 liter ULEV motor. A couple of months ago, the check engine
light came on, and along with it the idle got a little rough, and gas
mileage is down about 10 percent. I had the computer scanned at
Autozone, and they indicated that it needed a MAP sensor, which I
replaced to no effect. I had it rescanned, and it came up with codes
P1166 and P1167, which are the Primary O2 sensor and O2 sensor heating
circuit.

I ordered a generic Bosch O2 sensor and installed it as instructed. Even
after several weeks of driving (and I drive a lot) the light didn't go
out. I double checked my wiring, but everything looked okay, and even
redid the splices. With emmissions testing due in about 3 weeks, I took
the car to my neighborhood mechanic, who scanned it again. This time, I
am getting only a code P1167 (Primary O2 sensor heating circuit), and
was unable to clear the code, and the engine still idles a little rough.
I carefully checked out the sensor electrically, and I am getting
about 12 or 13 ohms across the heater, which seems reasonable. What is
more interesting is that I checked the voltage across the element while
it was running, and I seem to be getting about 9 volts across the
heater, but 14.2 volts from either side of the heater to ground.

I suspect it could be one of 3 things.

a.) The Bosch sensor is incompatible with the Honda ECU, in which case I
will have to shell out a couple hundred bucks for a new O2 sensor.

b.) A wiring problem, such as a high resistance connection between the
ECU and the O2 sensor. Should be able to track it down and correct it if
that is the case.

c.) A bad ECU

I don't want to have to buy a new o2 sensor if the problem is with B or
C, nor do I want to spend upwards of a grand on a new ECU, or probably a
couple of hundred on a junkyard unit if I am not absolutely sure. Any
ideas folks?

To respond off group, replace MyCaLlSiGn with my ham radio callsign

73 Bruce-N3LSY...-.-

Bruce,

Is there a way for you to make the same measurements (resistance, and
voltage across the heater element) on the other O2 sensor in the car?
This would give us a good idea of what the ECU would like to see. I
don't think your ECU is bad. Most likely you have a bad connection to
the new sensor. Your idle issue is harder to diagnose. When was the
last time the car had plugs/wires/air and fuel filter? Try a can of a
product from Chevron called Techron and see if it helps things.

Lets fix the O2 issue and see how it goes. If the readings from the
2nd O2 sensor are significantly different from the new one, try to go
back to where you got it and tell them they have given you incorrect
part. They may try to resolve the issue and provide you with the
correct one.

Fred wrote:
> Bruce,
>
> Is there a way for you to make the same measurements (resistance, and
> voltage across the heater element) on the other O2 sensor in the car?
> This would give us a good idea of what the ECU would like to see. I
> don't think your ECU is bad. Most likely you have a bad connection to
> the new sensor. Your idle issue is harder to diagnose. When was the
> last time the car had plugs/wires/air and fuel filter? Try a can of a
> product from Chevron called Techron and see if it helps things.
>
> Lets fix the O2 issue and see how it goes. If the readings from the
> 2nd O2 sensor are significantly different from the new one, try to go
> back to where you got it and tell them they have given you incorrect
> part. They may try to resolve the issue and provide you with the
> correct one

Plugs (o.e. type ND Platinum) were put in 30,000 miles ago, air filter
is fairly new, never had wires or fuel filter. Wires look pretty good, I
don't let them get oil soaked, so that is down the list. A clogged fuel
filter would show up as a lack of power or misfire when I put my foot
into it, which isn't the case, but it is probably due as well.

Checking the other O2 sensor might be a good idea, it is a Pain in the
butt to get to, at the very least I would need to get it on a lift or
some jack stands, but it is doable. I will check on it in the next day
or so.

Techron might not be a bad thing on principle alone, I have done nothing
to the fuel system since I got it new, except put whatever gas is
cheapest in it.

| I ordered a generic Bosch O2 sensor and installed it as instructed.
| the light didn't go out.
Your ECU chks your sensor's capacitance whenever u switch on ignition.
If your Borsh sensor has a different capacitance, your ECU will know a
correct sensor is absent, then may ignore any voltage from your Borsh
sensor as unreliable.
If 1 has a capacitance meter, 1 can chk each sensor ( when cool ) 's
capacitance.

| I checked the voltage across the element while
| it was running, and I seem to be getting about 9 volts across the
| heater, but 14.2 volts from either side of the heater to ground.
Why not chk the output of each sensor ?
http://home.flash.net/~lorint/lorin/fuel/lambda.htm

| a.) The Bosch sensor is incompatible with the Honda ECU, in which case I
| will have to shell out a couple hundred bucks for a new O2 sensor.
find a used sensor