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problem with o2 sensor HELP ME

  #1  
Old 05-21-2005, 10:36 PM
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Default problem with o2 sensor HELP ME

I bought my 98 ex with 120,000 miles on it and the check engine light came on 1 week later. It was the o2 sensor. I bought a new o2 sensor (bank 1) and replaced it . Couple weeks later the light comes on again and now it reads two codes ( low cat efficiency threshold, bank 2 o2 sensor malfunction) . I replaced the bank 2 o2 sensor to see if it would make both go out but the code came back for the low cat efficiency days later. I rode with this check engine light for a couple months unitl shortly when I replaced the cat with a high flow cat and bought the greddy evo 2 and bought dc sports headers for my car wich came with the o2 adaptor. My car was running great since for the first time i had no emissions restrictions but just days ago the light comes on again and it reads bank 1 o2 sensor slow response. Since i bought my car ive only ridden it about 3000 miles so the o2 sensor is just like 2000 miles old. Can anyone tell me what to do now since the sensor is almost new and already messed up? Could it be because i drove with the bad cat for a while and it might have messed it up? PLEASE HELP !
 
  #2  
Old 05-24-2005, 04:18 PM
Join Date: May 2005
Posts: 18
Default RE: problem with o2 sensor HELP ME

This can sometimes happen as the stock cat will have a certain back pressure but when you replace it with a high flow cat the sensor has to read the exhaust faster due to the high flow through exhaust.
 
  #3  
Old 05-24-2005, 04:37 PM
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Default RE: problem with o2 sensor HELP ME

ORIGINAL: DT Precision Tuning

This can sometimes happen as the stock cat will have a certain back pressure but when you replace it with a high flow cat the sensor has to read the exhaust faster due to the high flow through exhaust.
While somewhat true, it is highly unlikely that the backpressure difference would cause a slower response or damage to the O2 sensor. Here is what I found on the common cause of this code:


Oxygen Sensor Circuit Slow Response(Bank 1 Sensor 1)
Response time for heated oxygen sensor's voltage output to change from rich to lean, or from lean to rich, is 1 second or more during idling after engine is warmed up. (2 trip detection logic)

* Open or short in heated oxygen sensor circuit
* Heated oxygen sensor
* Air induction system
* Fuel pressure
* Injector
* Engine Control Unit

Make sure you have the adaptor connected correctly(make sure click and make contact). I have the DC headers and a high flow cat as well and haven't had any problems. Also make sure your O2 sensor is properly torqued and is making good contact(no leaks and properly brought to temp). Disconnect the battery for 30 minutes(maybe even overnight) and see if it comes back. Sometimes when you disconnect the battery for a short period of time the ECU will clear the code, but not the memory. It should clear the memory so it re-learns the new signals from the MAF sensor and O2 sensor with the newly added airflow. What kind of sensor did you buy? Was it a direct replacement or one of the splice your wires and connector type? If you had to do any sort of splicing you might start there and make sure your connections where done right and are solid. That is all I can think of right now. Good luck.


 
  #4  
Old 05-24-2005, 10:40 PM
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Posts: 10
Default RE: problem with o2 sensor HELP ME

thanks alot for your advice, well when i put my headers in i had to put some teflon tape around the part where it screws cuz it wouldnt screw back in right prob from all the time i took it out and in from changin my exhuast/cat but then i finally got it to screw straight and tightly but maybe that had something to do with it, also u dont think driving with a messed up cat for months couldve messed it up? After i put my headers in everything was fine till like after weeks when the light came on and then it went away by itself after like 3 days and after 1 week it came back and hasnt left since.... well i purchased a new one to see if its the o2 sensor that is messed up and ill go get it put in by someone to make sure its only like 20 bux and if it comes on again afterwards ill know its somethign else thats causing the o2 to go bad..thanks again
 
  #5  
Old 06-14-2005, 02:41 PM
Join Date: May 2005
Posts: 2
Default RE: problem with o2 sensor HELP ME

Sometimes a cracked header will cause the O2 sensor to fail.
 
  #6  
Old 06-14-2005, 02:53 PM
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Default RE: problem with o2 sensor HELP ME

man this stuff drives me crazy...so ok the CEL code reads o2 sensor bank 1 slow response so i decided to buy a new o2 sensor ones again thinking it was the problem and i get it put on and get the code cleared...about a couple days later the code comes back on and it reads the exact code ...o2 sensor slow response...i have no idea now what it could be..maybe the headers are just causing the comp to throw codes...obviously the sensor is not messed up.. its still new but its just reading something wrong and making it have a slow response..
 
  #7  
Old 06-14-2005, 04:11 PM
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Default RE: problem with o2 sensor HELP ME

have you checked your fuel system like previously mentioned. A slow response is being detected by the O2 sensor. That does not mean the O2 is slow to respond, it could very well mean the rest of the system is slow to respond to the comand of the ECU. Have you injectors flow tested, your fuel pump pressure tested and clean out the throttlebody really good. The TB build up a lot of carbon deposits and it could be making the butterfly hard to open and close. Change air filter and fuel filter. The O2 senses the Air Fuel mixture and reports back to the ECU so it could do the fine adjustments it needs to keep it at the proper ratio. If there is any lag or slow response by any of the systems(mainly fuel system) it will overshoot the desired value. In other words if the desired ratio is 14.5:1 and it reads 13.9:1 it will cut back on some fuel until it reads 14.5, but with the slow response by the time it reads the 14.5 the system may be set to 15.0 so to get it back down it will add fuel again and continue on with this cycle. Cats don’t last when you run rich, or extremely lean either but there are worst problems to worry about when that happens. That could be the reason your cat went out in the first place.
If I were you I would take it into a shop to get the injectors flow tested and the fuel pump pressure tested after you change the filters and clean the TB. You might as well get a professional injector cleaning. Just make sure you go to a shop that has a Snap On Motor Vac. It is one of the best services out there. You will definitely see the difference right away. There are things you can use at home to somewhat clean your engine but nothing replaces that professional injector service. Let me know how this all works out for you.
 
  #8  
Old 02-05-2007, 09:33 AM
Join Date: Jan 2007
Posts: 2
Default RE: problem with o2 sensor HELP ME

i went to replace the o2 sensor in my 2000 civic, because the the guy at the shop scanned it and said the heater inside the o2 sensor was shot. But to my surprise when i pulled the heat shield off i noticed that there was a crack in the headers coming from where the o2 sensor threads in. Now do you still think my o2 sensor is shot or is it just the fact that the header has a crack in it? I would like to figure this out before i put the new o2 sensor in, because if its not the o2 sensor i'll take it back and get my $100 back and put it towards a new header. Any help would be great.
 
  #9  
Old 04-07-2007, 10:11 PM
Join Date: Apr 2007
Posts: 1
Default RE: problem with o2 sensor HELP ME

I was just at the shop today. Told that my O2 Sensor heater was shot, and that is why my engine light keeps coming on. Does anyone know what part I need to fix this? I have looked in my repair manual but I am not finding anything, mind you I really havent looked that hard. Anyone else have this O2 sensor heater issue? Some insight would be appreciated. Thanks!
 
  #10  
Old 04-07-2007, 11:12 PM
riceburner700's Avatar
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Default RE: problem with o2 sensor HELP ME

what brand of o2 sensor did you go with? might have to find a used oem honda one or shell out the money for a brand new oem one
 
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