O2 sensor in OBD0

[GU357]

When i bought my B16 EG i was told the O2 sensor was dodgy so i had both of them replaced with a set of spares from a wreckers, the sensors were clean as a whistle.
got the car back and the mecahnic said the o2 sensor didnt seem to be the problem, becasue the engine light was on again.

i checked the ECU and noticed its throwing out the code 2 (secondary oxygen sensor)

when i check the voltage of the 02 sensor at the ECU in port C8 the voltage sits at pretty much 0.3-4 and doesnt move.
if i blip the throttle it doesnt move either.
however if i test the primary o2 sensor in C16 the numbers start jumping when i blip the throttle.

so does a broken o2 sensor always the a stable signal or no signal at all?

and how should i fix it? by a Brand new one?
i thought it seemed unlikely that the new sensors were broken too, but it is possible.
could it be the wiring by any chance? the colour of the wire going into that point doesnt match the one in this picture, but then i dont have any orange ones anywhere on mine.
http://site.hamotorsports.com/obd0reference.jpg

[bboyzell]

So you have a EG Civic with a obd0 Ecu running in it?

If you do then you should have the ecu connected to two 02 sensors.

what i would try to begin with is check the wiring on the secondary 02 sensor.
Would also suggest running a wire directly from the 02 sensor output to the ECU input.

[GU357]

yes i have a b16a5 connected to a OBD0 in my EG

but i was recieving a constant reading at the ECU already, which would indicate it is getting signal, but ill give it a shot incase it has been wired incorrectly.

[ECU-MAN]

check the signal at the sensor
do a continuity test from the sensor to the ECU for both sensors

ensure PO2 and SO2 are not cross connected.

if it all check ok then replace SO2

[GU357]

SO2 is 2nd sensor, whats Po2?


Edit, Oh primary o2 ahah

[ECU-MAN]

PO2 = Primary Oxygen Sensor
SO2 = Secondary Oxygen Sensor

[GU357]

just noticed something this ecu pinout diagram is counted in reverse fashion of the picture above.
http://www.clubcivic.com/board/showthread.php?t=90486&

[GU357]

grabbed a multimeter today and shoved it into the wires near the O2 sensors the Green one (primary) couldnt get a good reading the multimeter was showing it as being a negative number and i didnt have my leads mized up, but its pretty much sat at -0.02 and the secondary sat at 0.07.

i went in the car and checked the ECU plug c16 which is apparantly the Po2 was reading 0.07 roughly
but the pin C8 was reading 0.04.

whilst looking at the ECU i also noticed my colours are a bit different. the C8 is orange in the first diagram.
but mine shows it as blue/reddy
http://i1184.photobucket.com/albums/z332/GU357/IMAG0287.jpg

any ideas im stumped

also the colours of the cable coming out the plugs po2 is white thin cable, So2 is a thin orange cable.
not sure if they plug into anything else inside the engine bay for the colours to change at the ECU plug dunno if its normally like that.

but then again going by voltages u can tell its whacked.

[GU357]

according to this its correct though
http://www.dodo-upgrades.nl/pinoutOBD0_bestanden/image004.jpg

[ECU-MAN]

engine has to be hot when checking O2's without a heater

you cannot use a digital multi meter to test them either, you need a scope or one of those cheep jaycar O2 kits

see below links

http://www.ozhonda.com/forum/showthread.php?69868-DIY-PGMFI-Diagnostics-Code-1-PO2

http://www.ozhonda.com/forum/showthread.php?70236-DIY-PGMFI-Diagnostics-Code-2-SO2&p=1246964

[GU357]

ill try a continuity test tomorrow or tonight.
i need to get some longer leads.
also to do the test u recommend unplugging the c harness from the ecu? and to plug the lead in then, and unplugging the o2 sesnor and putting the lead into the plug (that should lead back to the ecu)

also is this the tool?
http://www.jaycar.com.au/productView.asp?ID=KC5195

[ECU-MAN]

that link is the exact kit I had in the DIY, Just I put it in a box.

yes you disconnect the O2's and the ECU connector when performing the continuity test just as described in the DIY

[GU357]

Figured out my ECU codes today, always knew it was 2 and 23 (Secondary o2 and knock sensor)
so i finally got a beeping multimeter (one that beeps when circuit is made)

turns out Primary O2 is plugged into the pin Knock sensor.
the secondary O2 is plugged into the pin for Primary O2 sensor.
dont know whats plugged into the Secondary O2 pin though, but im gonna guess its the knock sensor.

[GU357]

alright i depined the 3 wires so they were seperate from the plug.

and swapped them over to the right spots.
and no engine light!!
finally!!!
thought i was gonna go mad
seems like everything in that respect is ok, no more ecu codes n that.

thanks a tonne to ECU MAN! smart bloke.

still not sure why who ever did the wiring would just leave it in this state.
when i stripped the black tape back i saw where they went wrong though.
in order to keep the propper colours at the plug he has snipped the wires and crimped on wires with the right colour at that point he screwed up which white is which. and lead to this mix up.