B18C2 swap EG CEL code 41 O2 Heated Oxygen problem

[androoz]

Hey guys,

just did a b18c2 integra vtir swap on my JDM eg which originally had a D15B2 SOHC VTEC.

Ecu is throwing the CEL code 41 which after a lot of searching, is the O2 heater element.

I've tried to follow ECU-MANs diagnostic guide to test the wires to no avail.

The ecu is not throwing code 1 so am gonna say the o2 itself is functioning correctly, just the heater is not working.

I'm using the standard B18C2 OBD2 ECU which is running through a conversion harness to plug into the eg with is OBD1.

I have wired A6 DIRECTLY to the O2 signal wire (My OBD1 loom had A6 not pinned and connected to anything) and chopped it off the engine loom to mak sure there are no shorts anywhere. A11 is already getting 12V when the car is running.

Still have the cel on code 41.

The strange thing is that I've tested A6 and A11 without running the wire directly to the o2 and it definately gets 12v BUT as soon as I connect A6 directly to pin 4 on the o2, the 12V drops to 0.25 and remains like that unroll I remove the connection to pin 4 on the o2.

I have no idea what else to try.

Also should mention my jdm eg has 2 single wire o2 sensors and the wire that connects to the secondary o2 is currently unplugged with the b18, but reads approx 10v with the current setup.

Any help would be great. Thanks.

[dorikin]

you need to buy a 4-wire O2 sensor and wire it in properly, single wire O2 sensor doesn't have heater element.

and A6 is for the heater element ground

[thaizeg]

The o2 sensor androoz is using now is a 4 wire o2. Standard b18c one.

[yellows2k]

Is the operation of the car affected?

[dorikin]

Ohok I thought he was running 2 single wire o2 sensrs based on his post above

4-wire o2 sensor conversion wiring into EG:

1. o2 signal (white) - is already in the engine loom and chassis loom so no modification needed (obd1 - D14)

2. o2 signal ground (green/white) - already in your engine loom (b18c2) and should also be in the EG chassis loom (double check D22 on obd1 for continuity)

3. o2 heater power (yel/black) - should already be in both engine loom (B18c2) and EG chassis loom (but double check A25 on obd1 for continuity)

4. o2 heater ground (ora/black) - this one is in your engine loom but you need to add a wire in the chassis loom from LH strut tower plug to ecu A6 (obd1)

the last two are the important ones you need to check for CEL code 41
hope that helps

[androoz]

Sorry i shouldve been more clearer. Yes i am already using the 4-wire o2 sensor that comes stock with the B18.

The operation of the car seems to be not affected, VTEC hits ok, idle is fine. Not sure about fuel economy yet as im yet to run through a full tank.

As my car is JDM, it comes with a warning light with a picture of a cat converter on it. This light comes on when i remove any of the TWO o2 sensors that came on the stock engine (D15B2). This light still remains on after the conversion as i mentioned.

The wire that i am having problems with is 4. o2 heater ground/signal.

the o2 no.4 wire after the conversion was not connected to anything, as A6 on the ECU OBD1 had no pin in it.

Ive tried to connect it DIRECTLY (i cut wire no.4 off the o2 completely and run no.4 straight to A4 on the ECU) however this is causing a strange problem.

As soon as i connect wire no.4 to ECU pin A6, the voltage reading i get across A6 and A25 drops from 12v down to approx 0.25.

When i remove the direct connection to measure the voltage, A25 and A6 get its proper 12v as ECU MAN states it needs to be.

So im assuming this cannot be an ecu fault?

[dorikin]

first thing I would do is go back and double check the wiring.

- make sure you cut the right wire, wire 4 should be orn/blk

- then make sure you have the right pin in the ECU A6 (3rd from bottom left for obd1) and its connected using the right type of female pin
http://b16a2.kicks-ass.net/diy/pgmfi/ecu/PGMFI-pins1-2.jpg
- do a continuity test between o2 wire-4 and ecu pin A6

- then check po2h signal, multimeter red lead to battery positive and black lead to o2 wire 4.. should get 12v

[VT3C]

which ecu are you using ? AUSDM ? or JDM ?

u need to match the wiring harness+O2 sensor+ECU.. doesnt matter if it's AUSDM motor or not.. as long as the harness/ECU/)2 sensors match.

If you have missmatching harness that is OK, just need to match the ECU and the O2 sensor and hard-wire the O2 sensor directly to the ECU.

and this WILL affect performance as with the code 41 you'll be in OPEN LOOP (please correct me if i am wrong ECUMAN).

[androoz]

I thought that was the case, but I'm in the car testing it now.

I've cut both wires no.3 the o2 heater power and no.4 the o2 heater signal/ground off the o2 sensor completely and hard wired them to the ecu.

No.3 is going to OBD2a pin A11
no.4 is going to OBD2a pin A6

still no good. Like i stated earlier, with wire no.3 not connected, I get the proper 12v across A11 (heater power 12v) and A6 (heater signal/ground), however as soon as I connect up wire no.3 from the o2 up to OBD2a A6 the voltage drops to 0.25 across A11 and A6.

I'm using the audm ecu which came with the motor... We had the whole car here when we took the engine out.

[androoz]

I'm not having any problems with the o2 itself, only the o2 sensor heater which is code 41.

[dorikin]

shouldn't drop any voltage..

are you looking at the o2 plug wiring properly? ecu-mans diagram is looking at the plug from the wire side of the connector on the engine loom side

I think you might have the two black wires mixed up (3 and 4)

http://b16a2.kicks-ass.net/diy/pgmfi/ho2/PGMFI-Ho2-conn.JPG
^in this view, you would be looking at the back of the plug with the wires sticking out

[VT3C]

ahar.. i was the opposite (AUS chassis using JDM Motor and ECU) but had the same problem.. but the O2 sensor heater code will still throw open loop.

I dont think there will be any problem with the ECU or the Sensor - it's probably something like Dorikin said above. also note that a wire at the sensor may not be the same colour by the time it gets to the Firewall plugs nor the ECU.. so best to hard wire it as process of elimination.. once it's working u can trace back the wires in the factory harness and make it look pretty.

otherwise listen to what ECUMAN says - he fixed all my wiring issues remotely :)

[androoz]

I'm definately looking at the o2 properly. Wires no. 1 and 2 are green and white respectively.

Wires no. 3 and 4 are both BLACK. Wire no.3 gets 12v key on engine running... And wire no. 4 was not connected or run at all from the shock tower plug to A6 on the ecu.

I've even tried swapping both black ones wires around between A11 and A6 but still throws the code.

Don't know what I can do at this point.

[dorikin]

when you swapped the wires around between A11 and A6 did you first reset the ecu to clear the error code from the ecu memory?

failing that try another o2 sensor, your one could have a faulty heater element

[androoz]

I have tried another 4-wire O2 sensor from another B18... still same code.

Im hoping its not my ECU.

Talking to ECU MAN via PM so hope i can sort this out.

[androoz]

Still having no luck with this.

So far both O2 sensors (both from B18Cs) still behave exactly the same... code 41 each time the ECU is reset and the engine switched on.

ECU MANs diagnostic guide at http://www.ozhonda.com/forum/showthread.php?t=68798 states in step two:


STEP 2




Check the PO2H Signal. Connect the Red Lead from your multi meter to the battery Positive terminal. Back probe* the PO2H with the black lead to Pin 4 of the PO2H while the sensor is connected.

KOER* you should get 12v.


also check the PO2H signal at the ECU end at the following pin bellow



OBDO = n/a
OBDI = A6; note 1994 - 1995 Accord A11
OBDIIa = A6
OBDIIb = C1



If You do not get 12v replace the ECU



***** Its is always best to check sensor outputs at the sensor side *****

As it states in this part, checking wire no.4 with the sensor PLUGGED in, i do not get 12v (multimeter red lead on the battery, black lead on the wire no.4 o2 sensor side).

BUT when the sensor is UNPLUGGED, i get 12v across the battery and wire no.4 (engine loom side).

Im trying to get my hands on another ADM DC2 VTiR ECU to check and see if the ECU needs replacing.

Is there anything else i can do at this stage?

Cheers.

[androoz]

Also does anyone have any idea about the CAT LIGHT (pic of a cat light on the JDM cluster top far left) that came on when i removed the 2nd o2 sensor (for a catback exhaust) when the car still had the original JDM D15B2? This light is still on along with the code 41 CEL.

When i measure voltage on that one wire o2 (currently not plugged to anything as the B18C2 only runs one o2) i get a little over 10v from it.

[androoz]

tested my ecu in another car running the exact same engine which is also using a P72 OBD2a ecu and it threw the same code.

anyone have a spare ecu? must be OBD2a VTiR.

[androoz]

All sorted.

Thanks to ecu-man.

After A LOT of testing.. Turns out the ecu was at fault. Somehow the transistor which controls the o2 heater element inside the ecu was fried (along with some other things).

Anyone else with this problem, ecu-man is the man to help u out and can even repair your ecu for u.

[JDMugen.]

good to see you've got it all sorted mate (: