O2 Sensor 99-00 civic si questions?

[Eluce23]

I have a 99 si and my check engine light went on for the o2 sensor first for code p0141 ( heat) then i replaced it and it came on again for o2 sensor code p0133 ( slow response).. I don't understand what is wrong with it. when i drive i loose power when i'm accelerating a lot of times because of it. I really would like to fix this problem and would appreciate any advice.

 

[RonJ]

If you don't have an exhaust leak, the primary O2 sensor is bad.

 

[Eluce23]

I have already replaced it twice. it cant be that. i heard it could be a engine harness problem.. if so how could I pin point the problem?

 

[RonJ]

I have already replaced it twice. it cant be that. i heard it could be a engine harness problem.. if so how could I pin point the problem?

You car has two O2 sensors, primary and secondary. Which one did you replace twice? P0141 is a code for the secondary O2 sensor. P0133 is for the primary O2 sensor.

 

[Eluce23]

first it threw a p0141 bank 1 so i replaced that one, which is the one before the cat then p0141 went on again so i replaced the same one then p0133 just came on. but he same thing is happening. im loosing power while accelerating.

 

[RonJ]

first it threw a p0141 bank 1 so i replaced that one, which is the one before the cat then p0141 went on again so i replaced the same one then p0133 just came on. but he same thing is happening. im loosing power while accelerating.

Did you read my posts? P0141 is for the secondary O2 sensor, but you twice replaced the primary O2 sensor (the one before the cat). On your car the primary O2 sensor screws into exhaust pipe A before the cat whereas secondary O2 sensor plugs into the top of the cat. Did you replace the sensors?

 

[Eluce23]

would that explain the loosing power during acceleration? and are the two sensors the same, like would i be able to replace the secondary o2 sensor with a good primary o2 sensor that i have?

 

[RonJ]

would that explain the loosing power during acceleration? and are the two sensors the same, like would i be able to replace the secondary o2 sensor with a good primary o2 sensor that i have?

Look at the diagram I posted. Which O2 sensor did you replace twice? A bad secondary O2 sensor would not cause your problem.

 

[Eluce23]

ya thats what i thought. I replaced the primary o2 twice. im pretty sure i dont have an exhaust leak cause i would smell it. and i already checked for a intake leak and its not that. so im left to think its the engine harness.. what do you suggest?

 

[RonJ]

Step 1: Clear the ECU and drive the car to see whether P0133 repeats.

You would not necessarily smell an exhaust leak that would throw P0133.

 

[Eluce23]

ok i reset the ecu ill get back to you when i see what happens. thanks

 

[Gunner]

Any modifications to the car...header, exhaust or what not?

 

[Eluce23]

ya i got 4-1 dc headers, apexi exhaust air intake.

 

[tye]

would a gas leak cause this code to come on?

 

[00siboy]

Do you still have the cat or a test pipe? o2 codes can be set from a plugged cat or something causing your a/f ratio to be off. Although I think that if it was a heated o2 code it would not be set off by bad a/f ratio or plugged cat. In that case I would think that you would be setting cat efficiency codes.