Hondata

I installed a K-Pro for a customer and now the CEL is on with a P0131 (Heated Oxygen sensor low voltage) set.

I have replaced the oxygen sensor with a new one since the old one had some ghetto fab wiring extensions on it. In sensors it shows in the ECU data stream that the primary sensor is at 0.00V. WHen I test the voltage at the sensor and at the ECU it moves rapidly between 1.8 and 2.0V. Is the ECU not seeing the voltage for some reason? Is the ECU bad? Did I forget to click on something in the program? I have tried everything and it still wont show a voltage. Help! Thanks in advance.

The primary o2 sensor does not use voltage, it uses current, so using a multimeter to measure the voltage will not work.

Check the CEL flash count by shorting out the OBDII connector pin, since P0131 should not occur. Using the manual either follow the troubleshooting procedure for that error code or start checking the wires from the ECU pin to the o2 sensor connector.

Something like:

ECU A6 (red) -> C101 pin 19 -> C401 pin 19 (red) -> o2 sensor

ECU A16 (red/yel) -> C101 pin 13 (yel/grn) -> C401 pin 6 (yel/grn) -> o2 sensor

Early books are wrong in this area, with the relay shown incorrectly, later books are correct.

I had already done the book diagnostic even though there is no code for P0131. The voltage and current on the K-manager sensor list are both 0 and stagnent with the engine running. I am using a Snap On vantage graphing multi meter so it is good down to .01V and can pick up the 02 signal quite nicely when its there.

On a whim I popped off the cover of the ECU and checked the a-16 pin on the inside to make sure there wasnt a soft set pin in the connector. Viola! 0.00V on the inside of the ECU where 1.82V on the outside of the ECU. Somehow the pin got loose at the connector. I removed the pin and oinched it slightly and reset it. Now everything is Kewl. Thanks for the help.