Rep Power: 0

Hi All,

My first post here and hope if I can ask for some help. I have a 2004 Civic value package, daily driver/beater with 138K on it.

Check engine light comes on and take car to my buddy and throws his Snap On scanner on it and it shows P0135 I believe but it is the upstream O2 sensor. I go online to discountO2sensor.com and get one for $70, its a Denso part # NP2344123.

I put it in and check engine light comes back on with code P0134, so I think that is the other O2 sensor.

In doing some google research and that leads me to the question. Does my Civic have an O2 sensor or an air/fuel sensor? The difference in prices for the upstream one is substantial.

The exact wording on the original sensor reads:
DU2
Denso
192400-1160
11E20

I tried to find that exact part # and even tried Denso's site but to no avail.

So should I put the new one back in and just replace the other O2 sensor and hope the solves the problem or do I have an air/fuel sensor and bought the wrong one?

Thanks in advance for any and all help.
Rich

 
Rep Power: 811

04-05 civics switched to a wideband primary o2 sensor which is a ton more $$ than the regular narrowband the 01-03 civics had. call up an auto parts store, they should be able to find the right part number.

 
Rep Power: 0

The reason behind a primary Wideband O2 sensor is the time it takes for the O2 sensor to warm up. Wideband O2 sensor and made with a different material which allows you engine to go into close loop faster. At normal start up while the O2 sensor is not warmed up so the car will run rich which is when Car's produce the most hydrocarbon's. The price for the Wide band is normal. On my Supra my wideband reads and is warmed up WAY before the narrow band does.

As for answer you O2 sensor/air fuel sensor question yes. You O2 sensor IS you air/fuel ratio sensor. Where you doing some heavy driving up a big hill or something? just wondering how you burnt out both your O2 sensor at one time heh.

 
Rep Power: 0

Guys thank you very much for the clarification.........I will send back the $70 O2 sensor as I knew it was too good to be true when the rest were $150 or more.

Thanks again for your help I appreciate it.

 
Rep Power: 811

interesting. i guess its not possible to switch from narrowband to a wideband sensor due to ecu issues, it would be nice to have the sensor warm up faster cause i hate smelling nasty exhaust fumes on cold days and wasting gas. i wonder if you can wire the heater mechanism turn on before starting the car? like a pre-warmup if you turn the ignition on and wait 20 secs or something before starting the engine.

 
Rep Power: 0

I've heard of this Idea before. I'm not sure if you'd be able to directly change them. The problem is the way they recieve and send off information. Narrow bands and widebands are way different. I might have said this before but my wideband warms up like 4 times faster. your only problem with trying to create something to warm you O2 sensor is having a product that's easy and that will survive the harsh enviroment, also you'd be rich if you could create something like also. I'd have to look it up in one of my books but I think it has the Temp that's listed for narrow bands to warm up. give me a little bit and i'll look it up.

 
Rep Power: 0

Ok as I said he's that info:

Normal O2 sensors.
The ECU reads the sensor's voltage signal and alter's the fuel mixture, creating a feed back loop that constantly retrim's the fuel mixture. When a cold engine is first started the computer ignores the signal from the O2 sensor, running open loop. The default fuel mixture is set to run rich of the chemically correct (stoichiometeric) 14.7 air/fuel mixture. Most O2 sensors are electrically heated to try and warm the O2 sensor up to 600 degree's. narrow band O2 sensors are made from Zirconium-Dioxide elemenr (the tip) The sensors operate by a change in voltage.

Titania O2 sensor's
are made from Titania element. Operate effectively at lower temperatures and due to that can warm up in as little as 15 seconds and allow the system to enter closed loop.
These sensors operate NOT by voltage but by resistance. Low resistance indicates lean 1000 ohms which rich can be up to 20,000 ohms

Wideband O2 sensor's
Wide bands operate sending 0 to 5 volts for the signal. The problem is that narrow bands normally send 0 to 1 volts so circuitry conditioning maybe required.

 
Rep Power: 811

okay so it seems like wideband doesnt heat up faster, it can just start working at a lower temp. im still curious about the narrowband o2 heater circuit. like when it comes on, if it stays on, and how long it takes. it wouldnt be hard to tap the circuit and wire it to a switch that can be turned on before starting the car (im not sure how long it would take, couple mins?), and turned off once the car is started. the switch would therefore not interfere with the ecu control over the heater, just keep it on longer. some problems i would need to think about are 1. how long can the heater be on safely without burning up the sensor (if thats an issue), 2. how much current does the heater draw, so i can design my wire harness accordingly, 3. will the car be confused if sensor is already warmed up yet everything else on the car is cold (coolant, etc) and will this cause issues if the car starts to run in closed loop while the cat is not warmed up enough. either it might backfire and pollute more, or the cat might get ruined over time if exhaust is leaner than it should be. the whole stupid problem with this running rich stuff comes from the cat needing an ideal a/f ratio to function properly, and lots of heat. thats why ecu dumps fuel during warmup so the cat starts working faster. in the old days, cars would actually run lean mixtures when cruising, because theres no cat to worry about damaging, and thats why many newer cars have such terrible gas mileage. average mpgs 20-30 yrs ago for small cars was 40-50, today its 20-25. even todays hybrids barely break even with older cars mpg. and hp did not increase much, if any.

also i think i can tell when my car goes into close loop. if i let it sit and warm up for a few mins, eventually the rpms will change for a second and i think thats when it happens.

 
Rep Power: 811

i can just check my electrical manual to find the + - heater wires, then hook them to a switch. i still need the amp draw of the circuit. if its low enough, i may not even need a relay harness (altho i have one installed for hids thats not being used). then i could wire the sensor to a switch i have in the car already below the driver dash. the only other question i have is how long does the sensor take to reach its max temp? if only a few seconds, its not worth doing the mod. im starting to think the heater circuit is just there to give a small boost and make the sensor warm, while the exhaust gas is what heats it to a workable heat range.

 
Rep Power: 811

okay im getting more confident about this. supposedly the heated sensors run much hotter than non-heated versions and this causes them to last alot longer due to burning off carbon deposits. so it seems like the heater stays on all the time. the mod is going to be finding a way to turn it on before starting the engine. first thing i need to check is whether the sensor heater gets hot when you turn the car to ON position. if it does, im already done. just leave car in on position for few mins before starting the motor. if not, i need to find a way to tap the heater circuit to the ignition switch so i dont forget to leave it on by mistake. still need to know the amp draw so i can figure out the best way to wire it up. i think this might work. hey i think i just answered my own question lol. after starting the motor, the key is in the ON position, so i think the sensor heater has to come on with car in ON position. unless there is some switch when starting the motor idk. i will find out and post back. im just gonna turn the car on and hold the sensor to see if i feel it warming up.

 
Rep Power: 811

*confirmed from electrical manual. heated sensors (both of em) are HOT in ON position. so im gonna take some temp readings and see how long it takes to get to full temp.

 
Rep Power: 811

ive been reading that most heated sensors take 20-60 secs to warm up. the body will feel warm, but the tip will be hot. i sure wont mind waiting a minute with car in ON position for it to warm up. i will still measure the temps tho to be sure its turning on.

 
Rep Power: 0

The operating temp. of a wideband O2 sensor is lower so it doesn't warm up faster but it is able to read faster at lower temps.

1. how long can the heater be on safely without burning up the sensor (if thats an issue),

I think you can leave it on the whole time. I believe it's on so that while the engine is at an idle or or the car is stopped the sensor doesn't cool down.

2. how much current does the heater draw, so i can design my wire harness accordingly,

I believe you solved this issue

3. will the car be confused if sensor is already warmed up yet everything else on the car is cold (coolant, etc) and will this cause issues if the car starts to run in closed loop while the cat is not warmed up enough.

Ok this I believe shouldn't be an issue. When the sensor are not warmed up the engine with run at stoichiometeric (14.7 A/F) If the sensor are preheated to the required 600 degree's then it will allow the ECU to go into closed loop faster. The only issue is what it could do to the Cat. I'm guessing that if this is done that it would actually take longer to warm the Cat up (lower cylinder temp due to a less lean condition.

You are correct about the Temp for the heater. If it runs like a MAF sensor then when you shut the car off it should do a quick cleaning cycle which heats up to some crazy amount (that is a big IF)

When I'm running my supra and i'm letting it warm up my wide band warms up with in 10 seconds. In order for my Normal O2 sensors to warm up it takes a long *** time as in Minutes. My normal A/F ratio while idling is around 13.9 (stoichiometeric for best Torque) and when I'm wide open throttle at 13 psi i drop down to 10.9 A/F.

Well it sounds like you've already started. I'd like to see how far this goes and see what comes out of this. I'm predicted it'll work fine. If this works I can see a DYI being typed up lol or at least a thread so that we can continue to monitor your set up. I hope this works because i'll want to do it with my Civic too haha. Keep me posted!

 
Rep Power: 811

well i hope its as easy as just turning the car to ON position for 60 secs before starting the engine. everything ive read says the sensor will get power already. that way it has a head start before the engine comes on. im gonna feel the sensor and see if its warming up. i think it will.

 
Rep Power: 0

Just dont burn yourself lol that would suck but it's all in for the sake of science!

 
Rep Power: 811

nah the sensor only just got warm after about 20 secs, then i felt no difference. on hot days it prolly wont matter, but on cool days i will try and let it sit in on position for 20-60 secs. better than being cold.

 
Rep Power: 0

any new info on this? have you tried it in the morning?

 
Rep Power: 811

i just let it sit for 20 secs in the on position til the engine light goes off, then i start and warm up like normal. i havent noticed any difference, so i think the exhaust gases get much hotter than the sensor. so i dont think it will do much other than a slightly faster warmup which isnt noticable.