I was driving a new car I just got a week ago which is a 2005 Honda Civic HX and suddenly while driving the check engine light illuminated, I got my scanner in and check for the codes and I got those two:

P0144 - Heated Oxygen Sensor (HO2S) Circuit High Voltage Bank 1 Sensor 3

P1130 - Heated Oxygen Sensor (HO2S) Circuit Low Variance Bank 1 Sensor 1

So I guess this is a failing O2 sensor the one in the headers and the one after the cat? can a failing O2 sensor in the headers cause the cat sensor to fail because the car is running rich thus the catalytic converter is not doing its job? or what would cause both of them to fail at the same time? are the sensors the one I am thinking of correct?

  • Interesting. I thought most cars have only 2 and not 3 sensors per bank. Anyway, if two sensors fail at exactly the same time, it looks a bit suspicious. The failure could obviously be elsewhere than in the sensors.
    – juhist
    Mar 18, 2017 at 8:54

1 Answer 1


Your DTC descriptors are a bit off.

P0144 is, Third HO2S (Sensor 3) Circuit High Voltage.
P1130 is, Secondary HO2S (Sensor 2) and Third HO2S (Sensor 3) Replacement Required.

Check your voltages at sensor 3. Check the wiring for a short to power or an open on the low reference. make sure you have bias voltage when the sensor is disconnected. If you do need to replace sensor 3 it's recommended to change both sensors 2 and 3 at the same time.

Your engine would have to be running rich already (Past the point of the computer being able to maintain fuel control.) for it to reflect in the downstream sensors and can be confirmed by looking at fuel trims. If the cat were bad you'd see cycling on the downstream sensors.

Note on some cars a bad rear o2 will throw off the front o2/AFR sensor setting a DTC for the front o2/AFR sensor or a lean condition.

  • 1
    Sensor 2 and Sensor 3 are placed fore and aft of the NOx adsorber catalyst used on this model. They come as a pair in a kit from Honda. They are a matched set and are required to be replaced as a set. This is the meaning of the description of the P1130 code Mar 18, 2017 at 16:57

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