Error Code 41 - O2 Sensor

[ewendc2r]

Hey all -- Glad I can finally make a thread lol

I have a dc2r that is running incredibly rich at the moment - about 250km's to a full tank driving 'normally'.

My mechanic hooked up his diagnostic computer to see where the problem was, (i.e. if it were a failed o2 sensor, or other problems making the o2 sensor trip out). Essentially the o2 sensor seems to be giving readings throughout the rev range, and they seem to be right. I previously that day thought I saw a Code 5 (MAP Sensor) come up, but may have mistaken for Code 41 (i.e. still five engine light flashes).

The light came on after a 'showoff session' with a friend recently, the engine was operating above 6500rpm for the majority of the time and bouncing off rev limiter between gears.

The engine is also idling at about 1100rpm most of the time and sometimes drops to 900rpm.

I am running a full mugen exhaust and trust intake - Is it possible the Mugen headers have cooked the o2 sensor? Has anyone else experienced this?

I have tried to provide as much info as possible -- Your help is appreciated.

Anyone experienced a problem like this? -- The o2 sensor is going to cost around $700 for a aftermarket item (that won't break again, if it is indeed actually broken) so then I would like advice on what you think I should go for as a fix. I.e. Should I just go open loop aftermarket ecu (PowerFC, Motec etc?) I have heard idle smoothness can suffer with aftermarket on these engines,

[Weq]

man dont pay $700 for a o2 sensor. u could get a wideband with narrbowband output for $500 :(

[ECU-MAN]

i think you shoul dreset your ecu and go for a spin.
if there is a problem the ecu will log a code.

tell us what the correct code is

code 41 is 4 long flash and one short flash

[ewendc2r]

Yeh mechanic was estimating (i.e. based on a ek civic race o2 sensor he bought recently .. he said he wasn't too sure but thought around that money).

What's the point of a wideband with narrowband output? i.e. can it be wideband for aftermarket ecu's? (sorry .. Electronics are not my forte).

[ewendc2r]

i think you shoul dreset your ecu and go for a spin.
if there is a problem the ecu will log a code.

tell us what the correct code is

code 41 is 4 long flash and one short flash

Yep -- Exactly what came up :) I swear I saw 5 long flashes the first time tho :P .. was probably a mis-read though.

41 is the code.

[BLKCRX]

You should be able 2 pickup a 2nd hand o2 sensor from a wrecker for 100$ easy, or borrow one off a friend you need a 4 wire Honda sensor 2 black 1 green 1 white sensor.
$700 from Honda is way way over quoted. from the sounds of things get your hands on a obd1/2 scan tool and read the voltage for long term and short term fuel trim, this will give you a idea of what’s going on. Either way something is’t correct. Replaicng your ECU won’t solve the problem, just bandaid it.. fix the problem by fixing the problem don’t make a work around solution for it.

[ewendc2r]

BLKCRX -- Sorry, I mean if it is the o2 Sensor that is Cooked, whats stopping it from cooking again? i.e. If it is going to fail again, then I'd rather invest in a good ecu (PowerFC,Motec likely, tho I wanna know more about Pro ECU :P) and get rid of the o2 sensor all together :)

[BLKCRX]

You need some kind of o2 sensor regardless of the ECU so you can swap between open and closed loop, for a street car a narrow band sensor does a fine job at keeping cursing air fuel ratios within a reasonable limit. Sure you can stick a ECU into open loop and not use negative feed back but, meh its not how I would tune a street NA car. As for a sensor going bad again well how many Honda car’s have Honda made millions ? do you see everyone complaining about a bad o2 sensor, ??? if its in fact your sensor maybe you were just unlucky maybe its faulty, maybe you drove over something and it destroyed it, there’s a 101 reasons why. Your standard ECU if everything is working correctly should give you fairly good fuel economy. Its not the ECU causing the problem but more to a effect a sensor or something down stream causing the problem. Replacing the ECU and leaving the problem there is’t a move forward.

Regards James

[ewendc2r]

Ok ok -- This is what I thought.

If the o2 Sensor failed, then the trim settings might be set to full rich (fail safe). These trim settings shouldn't be a huge margin less or more than the ECU is telling the injectors / engine to do anyway right? (as in, the trim setting wouldn't make it run full rich / any throttle position, rather a small adjustment trimming the setting).

Either way, shouldn't the MAP sensor work this out as well?

So why am I using SO much petrol? (I have black carbon residue on the back of my car after 1-2 days of driving).


:confused -- Thanks for the input guys.

BLKCRX -- Also my mate has a toyota sprinter running M4 ecu and 190hp - He has no o2 Sensor however would like one for economy. It is a 'streetable' race car but built for track in particular). If the ECU is tuned properly then is there really a need for an o2 sensor? I understand what you are saying about not fixing the problem, but if the problem is resulting from a broken ecu sensor, then getting a new computer with a new tune and by passing this o2 sensor with bad feedback would solve the problem.

I'll check wreckers -- Which model cars share the same o2 sensor? (I have 2000 AUDM DC2r)



EDIT- Re Read your post BLKCRX -- What you are saying is that if the O2 Sensor is ****ed and the ECU is fine, then just replace the ECU and wallah all good. What I am worried about is the o2 sensor failing again (if it is indeed caused by the mugen exhaust).

Thanks guys.

[BLKCRX]

Dude keep reading my posts again ;)

Your ECU is fine, I very very very very much doubt your ECU is sick, a ECU sensor ie your o2 sensor could be a possible ability but that’s the sensor its self, all the ECU does is read the voltage from the sensor, replace the sensor fix the problem.

Get or borrow or get a 2nd hand sensor plug it up reset your ECU (short / long term trim) n see how you go. The Map sensor has no real.

Yes you can run ECU’s without an o2 sensor but having a negative feedback control only improves your fuel economy, as there is constant fine adjustments making things closer to perfect. Without a o2 sensor the ECU is like driving your car with your eyes closed… I like 2 drive my car with my eyes open !!

[ewendc2r]

I hear ya, and I am not communicating myself clearly -- I know the ECU is fine. I am now trying to narrow down the central issue.. Looks like possibly a vacuum leak?

[tinkerbell]

you need to do what ECU-MAN said: reset the ECU and then go for a drive and see what codes come up.

we need to know what the code is to be sure of what your problem is.

http://members.iinet.net.au/~joannepulis/sparefiles/ECUresetDC2.jpg

[MoDCoN]

i think he knows what the error code is - 41 = o2 sensor

what he is saying is why has the sensor died? and secondly, can i run without one, like my friend with his sprinter. blkcrx has answered this - yes its possible to run without one, by why would you? get one cheap, it will improve your efficiency.

[tinkerbell]

if that is the case MoDcOn can you explain this:


My mechanic hooked up his diagnostic computer to see where the problem was, (i.e. if it were a failed o2 sensor, or other problems making the o2 sensor trip out). Essentially the o2 sensor seems to be giving readings throughout the rev range, and they seem to be right.

[ewendc2r]

if that is the case MoDcOn can you explain this:

We got the CEL to flash 4 long, 1 short. Code 41 (o2 Sensor)

Then we hooked the Diag machine up and .. no code! what the? So took it for a drive, and code came up, however the o2 sensor was still giving readings.

bizarro!

[MoDCoN]

We got the CEL to flash 4 long, 1 short. Code 41 (o2 Sensor)

Then we hooked the Diag machine up and .. no code! what the? So took it for a drive, and code came up, however the o2 sensor was still giving readings.

bizarro!

[ECU-MAN]

because code 41 is primary oxygen sensor heater failure, not the O2 sensor its self

what that means is the heater element inside the O2 sensor is no longer heating the sensor, or its heater element has become open circuit or high resistance.

the part that measures oxygen content is still functioning ( or you would have code 1 as well ) , this is why when the engine warms up you get a reading from the warmed up sensor.

[civiceg9]

There are ways to bypass the 02 sensor
WHy get a 2nd hand one while u can get a new one for much cheaper
Get a NTK OXYGEN SENSORS (made by NGK), the are usually less then $100.

[BLKCRX]

NKG sensors are not 4 wire, and have a different voltage output than the standard o2 sensor. how can you use a sensor which has a different output ! it will fool the ECU into reading the incorrect voltage, this is very bad advice, it would turn his problem into even more of a problem. Stock ECU needs the Stock Sensor.

Regards James

[civiceg9]

NTK/NGK does have a o2 sensor for Honda list with 4 wires and using a OEM Honda connector. Sensor Part No. with connector is OZA502-E26
This is a stock OEM replacement sensor. If I am not mistaken they manufacture for Honda too. as I know my stock one writen on the sleeve of the oxygen sensor.

u can find this part as listed on there NGK parts book and website; and can be purchased at your local parts store. If have questions maybe just ring NGK up.

[ECU-MAN]

NTK/NGK does have a o2 sensor for Honda list with 4 wires and using a OEM Honda connector. Sensor Part No. with connector is OZA502-E26
This is a stock OEM replacement sensor. If I am not mistaken they manufacture for Honda too. as I know my stock one writen on the sleeve of the oxygen sensor.

u can find this part as listed on there NGK parts book and website; and can be purchased at your local parts store. If have questions maybe just ring NGK up.

they sure do, also work well

only down side is you have to wire them up, as they dont have the Honda 4 pin connector on the end, you have to connect your old one to it. but worth the hassel

[ewendc2r]

How do I locate a vacuum leak if there is one, how do I determine what may have caused the sensor to fail? If the o2 Sensor heater is returning a CEL then shouldn't the sensor itself still be working?

Totally confused.

[wynode]

How do I locate a vacuum leak if there is one, how do I determine what may have caused the sensor to fail? If the o2 Sensor heater is returning a CEL then shouldn't the sensor itself still be working?

Totally confused.
Yes the sensor should still be fine.

The heater is just used to bring the 02 sensor upto operating temp quickly so it gives the correct reading to the ECU quicker. "Older" cars didn't even have a 02 heater.

[ewendc2r]

Yes the sensor should still be fine.

The heater is just used to bring the 02 sensor upto operating temp quickly so it gives the correct reading to the ECU quicker. "Older" cars didn't even have a 02 heater.

So can I turn the CEL off for that item? (i.e. Ignore that code) so if anything else goes I get a CEL again (safety wise for the engine of course).

And then the question remains, why am I only getting 250-300kms out of a full tank?! Suggestions? Power is still good (well, not noticeably down anyway).

[wynode]

So can I turn the CEL off for that item? (i.e. Ignore that code) so if anything else goes I get a CEL again (safety wise for the engine of course).

You can't make the ECU just 'ignore' the faulty heater. Just replace it :)

[ewendc2r]

So -- Any reason why the car is running so goddam rich?

[ECU-MAN]

blocked air cleaner, map sensor problems, ECT or IAT sensor.

[ProECU]

You can't make the ECU just 'ignore' the faulty heater. Just replace it :)


erm, yes you can, but I agree, replacing is the best option

[wynode]

erm, yes you can, but I agree, replacing is the best option

So how can you stop the ECU from throwing that code even if the heater isn't working?

[ProECU]

disable it in the code

[tinkerbell]

So -- Any reason why the car is running so goddam rich?

see post #12:

http://www.ozhonda.com/forum/showpost.php?p=473105&postcount=12