I have a 2002 Civic LX. After replacing the cylinder head gasket (and ancillary gasket that came with the kit) I am not getting the P0131 code once the car is warm. See below:

1) The car runs fine.
2) I hooked up my ODBCII scan tool. The voltage on the upstream fluctuate between 0.8 and 0.1,
3) As the car warms up the the car continues to fluctuate and then the voltage goes to 0 and the check engine light comes on
4) I put in a new 02 sensor and it does the same thing.
5) I have checked the hoses and they all appear to be fine.

Could someone give me some advice?

Thanks!

 

The P0131 is a circuit code for O2 sensor low voltage at the bank 1 sensor 1
You verified that the voltage does go to 0 volts
Now see if the O2 sensor is doing that or is the wiring causing the voltage to drop
Or ECM is pulling down the voltage or short or open circuit

 

would like to know if the sensor is an aftermarket or Honda oem sensor.