Jim Yanik <jyanik@abuse.gov> wrote in
news:Xns9848C1F781787jyanikkuanet@129.250.170.86:

> "TeGGeR®" <tegger@tegger.c0m> wrote in
> news:Xns9848BE6E0916tegger@207.14.116.130:
>
>
>>
>> Do you know the EXACT alphanumeric numeric code that was recorded?
>> This is critical. Most O2 sensor failures these days have to do with
>> the heater circuit.
>
> I wonder why the O2 sensor needs a heater? It's already in the hot
> exhaust. Perhaps to get the sensor up to operating temp quicker? (to
> shorten the open loop time)



The heater is intended not only to ensure fast warmup, but to make
certain the O2 sensor always remains above 750F.

The oxygen sensor needs to be at 750F to be fully operational. Even
though combustion chamber temperatures are about 2,100F, it is possible
under certain circumstances for the exhaust temperature to drop below
750F by the time it reaches the sensor. This would result in degraded
performance and increased emissions.

In addition, EPA regulations force the newest cars to use a variant of
the oxygen sensor called an "air-fuel ratio sensor". This particular
design requires to be at 1,500F before it is fully functional, and that
temperature is impossible to maintain without a heater.



--
TeGGeR®

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/