I Need help with air fuel ratio?

Question

Hey Everyone

I have a '04 Honda civic, but i swapped the motor (k20a3 '02 acura rsx base). Im having issues with the air fuel ratio, its WAY too rich

I have a k-pro in the ECU which gave me the following error code:

P0135 Primary Heated Oxygen Sensor (Primary HO2S) (Sensor 1) Heater Circuit Malfunction

i tried replacing the o2 sensor and it didn't do anything, it would run for about 10 seconds before the check engine light came on.

i was looking around on here and tehy said to check the MAP/MAF sensors timing, plugged injectors etc, but the k-pro would give me an error code if it were anything like that.

Anyone know of something i can do?

Answer 1

did you check the wiring and the fuses

An engien without the o2sensor runs on preprogrammed mode wich always makes sure engien is runnign rich cause its better to have too much then not enough unti lyou fix the o2 problum.

Answer 2

If you would have read the DTC fault description carefully, you would have narrowed down where to look.  "HEATER CIRCUIT" this means either the heater element in the sensor is bad, but we know it's not since you have already replaced it, or you do not have power or ground to the sensor's heater element.  Do both engines use the same O2 sensor?  My guess is that they don't and the wires do not match up so that the 12v+ ignition source or ground is not getting to the proper terminals on the O2 sensor connector.  You'll need a wiring schematic so determine which wires are the sensor hi and sensor low, and which are the heater power and heater control.  Once you have the sensor hi and low wires going to the correct location on the ecu, then get the power and ground right.  You can test if the heater is working or not by adding a ammeter, any good DVOM usually has a 10 amp meter in it, in series to the power feed to the sensor.