O2 sensor OEM or aftermarket

I am no expert, but I installed a Bosch 02 sensor in my '91 Civic Si
this past fall and have found it to work fine. The original did not die
(no check engine light), but I suspected it was 'lazy' as described in
the usenet archives and on various webpages. I seem to be doing a little
better economy wise and my idle is more consistent and regular. I guess
I'll see how long it lasts. I had around 135k miles at the time, and the
sensor in the car was OEM style, maybe original. The Bosch sensor is
noticeably different, it has a larger diameter body. If I understand it
correctly, it seems that an 02 sensor wouldn't really have to be OEM
just by its relatively simple design and function.

My $0.02,

Mark

 

It is time to change the oxygen sensor on my 95 civic and I can get a
Bosch with OE connector at less than half of what the Honda dealer
wants for an OEM (Denso?). Is the Bosch a good choice or should I
make the dealer rich?

 

It's more expensive I know, but OEM is a MUST. Aftermarket O2 sensors
are known for not working properly especially in import cars.

 

The cheapies are fine, but won't last as long as OEM.

 

How well do aftermarket O2 sensors work in Japan?
Better, since they are domestic?

 

Bosch is a good sensor, the make many of the ones in the American market.
I'd use it. Avoid the ones with the plug you wire on, while they work, there
a pita to do, sorta

 

I had to change my o2 sensor (actually it's a Bosch) on my Honda Civic 98
DX, and let me tell you I rather have paid more to get the OEM from Honda...
The fuel consumption is way off and my car is drinking like a Homer Simpson
with Duff beer... no kidding..

my advice: OEM or nothing at all

Jason

 

hm. good to know. the top primary heater circuit (gotta love scantools!)
O2 on my 98 hatch took a dump last year and i replaced it with one from
the local stealership. $220, but they were the only people to have one
in stock. autozone and kragen- both out. shit- forgot to try napa i
didnt wanna wait for mail order and run the risk of screwing the
catalyst up. besides, it was stalling at idle.

just had the biannual smog check, and almost all the numbers are *lower*
than the last time! a couple are a tick or 2 higher, but all are below
average, and wayyyy below the limit. 2 years ago, i had some numbers
that were pretty near the limit.

 

You can Blame the o2 sensor, but what else is wrong? Regardless of what
brand they are they work on the same principal, and the numbers won't effect
the economy unless dead or off. here is something I wrote concerning this
subject.

OK, Here it goes 02 class 101 (and catalyst efficiency)


The O2 sensor generates its own voltage, and without my meter I couldn't
tell you, BUT trust your scanner if it gives you a voltage reading. The
first o2 sensor switches when the engines running, you watch it go low to
high (sometimes .020 volts to a high of .900 volts (Milivolts??)
It should click along at a steady pace, picking random numbers into the
700-900 range then low again in the 100's
It is looking for Oxygen. This sensors job is to tune the car if it starts
to run to rich; i.e., if too much fuel starts feeding into the cylinders,
for whatever reason, the o2 sensor will start showing a higher range of
numbers, and the computer will start decreasing the injector pulse to
decrease the amount of fuel.
Anyway, a 02 sensor can get sluggish or it can freeze at a random number
then it lies to the computer that will still try to correct it. but usually
this sets a 02 code...

Now that basically describes the 02 sensors operation. The 2nd o2 sensor's
job is to check to see if the cat converter is doing it's job (Generally,
most 02 sensors are the exact same part excepting for the plug and wire
length). It also switches the same as the first one but at a slower or
reduced rate. If your scan tool shows the aft 02 sensor stuck, I'd try it
first.
If your second (aft) 02 sensor is switching at the same pace as the first o2
sensor (the numbers won't match) then chances are the cat is bad.


Now if you are having a fuel consumption problem you need to look at the
computer and look at the short term and long term fuel trim. This tells you
if the car has been trying to adjust the fuel delivery based on all the
other data it gets. If you hook up a scan tool and watch the O2 sensor work,
and it's going from low to high and back again, then it's doing it's job and
no other brand o2 sensor will do it any better.
You can't take one part and blame everything on it without knowing how it
works and works with the car. I've been to many classes on this stuff and
still am trying to sort it all out, got another class on Monday and Tuesday
night. We will be looking at graphing lab scopes analyzing the injector
pulse width and the ignition spark in reference to trouble shooting
misfires. Good thing there isn't a test....



--
Stephen W. Hansen
ASE Certified Master Automobile Technician
ASE Undercar Specialist

 

I would agree that the brand of O2 sensor is not responsible for the
increased fuel consumption. The transfer characteristics (the
relationship between oxygen content in the exhaust and the output
voltage from the sensor) of O2 sensors vary widely. Some are virtually
digital, i.e. the voltage is high (~900mV) when the O2 content is below
a certain threshold, and low if the oxygen content is higher than the
threshold. Other sensor have a fairly linear response around
stoichiometric air/fuel ratio. If you get the wrong type, I can
certainly see that fuel economy would be affected.

 

Here in Washington they don't even run a tailpipe test on the OBD II cars,
96 and later. They just scan the computer for any trigger codes and if
there are none you pass. I actually prefer to see what is coming out of my
pipe.

 

here, they do everything. put the car on a dyno, plug the big smog
computer into the OBD2 port, check for codes, test at 15 and 25mph, test
the gas cap pressure.

 

An interesting note: Bosch invented the o2 sensor and the first car to use
them was Volvo in the late 70's.
As long as the 02 sensor switches at a decent pace and the numbers go from
high to low, there isn't much more that it can do. IF the car is running
rich (high voltage) or lean (low voltage, then the o2 sensor starts hanging
around those numbers then the ecu starts adjusting the injector pulse to try
to correct the problem.
Our shop Forman worked for Nissan for years and was "the problem solver "
for northern cal (when he lived there) and Oregon in the more recent past.
He told this story: A Nissan 300zx 6 cyl. drove fine around town, but when
the once drove out of town at the 50 mile range the car would start to run
like sh*t, as the owner said "on 3 cylinders" So my boss took it on a drive
and sure enough at the 50 mile range it started running bad. He had a Nissan
specific computer hooked up reading all the data, he noted that 1 bank of
the car's 02 sensor was reading 2 volts! the car was trying to correct the
o2 sensor by shortening down the 3 injectors pulse width until there was no
fuel coming out, and the car was running on 3 cylinders. He had to
disconnect that 02 sensor to get the car to run to get back to the shop. He
called the higher ups at Nissan to tell them what he found and was told that
it was imposable for an 02 sensor to get above 1 volt, so the sent them the
computers saved dada on the test drive.