Honda S2000 AP1 - just installed KPro - got error DTC P0135

[pipka76]

Hi,

so I have just finished KPro install on my S2000 AP1. My car is pretty much stock (CAI + cat back). The car starts fine and idle. After few seconds after start I always get the code 41 (P0135 Primary HO2S heater circuit malfunction).

I have checked this error against Helms (for s2000). Wiring is ok, battery voltage is on the correct pin of the sensor terminal (but not between them). HO2S has 3.6 Ohms on heater pins (helms says around 3.3).

EDIT: I have wideband plugged after cat. During first seconds of idling shows around 16 to 17 AFR. It seems like that exhaust gases are extremely hot, because after few secs since start I can see hot air coming from the exhaust header.

I don't know what else to check and if I should consider my o2 sensor as bad one. Please help. I'm attaching calibration and datalog recording for few seconds from engine start.

UPDATE: I have took out my primary O2 and tried to heat it up using torch and measure output voltage. It works pretty good. Also impedance of heater pins is ok I guess (around 6 ohms when sensor is hot). I have checked service manual for RSX and there is 10 - 40 Ohms expected for secondary O2 sensor? So question came to my mind ... Do I have to change my original S2000 primary O2 for something else or it should really work???
I also have noticed that KPro is showing 4.08V for O2 sensor all the time.

Many thanks. George

[Spunkster]

The stock S2000 primary o2 is not a wideband. IF you are getting an error for the heater not working then you probably have either a wiring fault, or the sensor needs to be replaced. Heating the sensor with a torch is not a good way to test it and more than likely will damage a working sensor. I'm not sure what wideband you are referring to.

[pipka76]

Yes, I know, sorry about that confusion. I have stock narrowband primary o2 sensor and in the secondary location (after cat) i'm using Innovative wideband.

However I have solved my problem with o2 sensor. It wasn't bad sensor or wiring, it was broken connection inside Hondata ECU. I'm attaching an image of burned connection coming from pin C1.
I don't know how that happened, but it is a shame that Hondata extension board is not able to handle the same current as the o2 heater circuit fuse is designed for (15A).

When bridge that interrupted burned path, I can get closed loop working perfectly and without errors.

[Spunkster]

We have sold hundreds of these without any problems. There must have been something that kept the fuse from blowing and caused the track to burn.

[pipka76]

I really doubt that thin track can withstand more than 5 Amps. But I'm not trying to argue over this. Just providing a feedback.
My problem with this is solved and I'm happy that can continue with tuning.

Thanks for responses.

[Hondata]

The O2 sensor heater normally draws 1 map, maximum 2 amps. The track is sufficient.