2000 Accord SE O2 sensor problem
 

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...-.-