A few hundred miles ago my 1999 Dodge Durango 5.9L engine check light came on indicating a bad B1S1 O2 sensor. The original sensor.
I replaced it with a Denso and after about 175 miles the light came on again. This time with a P0135 indicating a problem with the heater circuit or lack of voltage supply. Checked voltage and it showed OK. So I replaced the sensor again.
About another 175 miles and the light came on again with the same problem… P0135. Measured the voltage and it showed OK. Measured the resistance and it showed 6.6 ohms. It seems to be within specs. Out of curiosity, I retrieved the replaced sensor and it also showed 6.6 ohms.
Other than the bad heater circuit, this and the previous sensor work just fine.
I am a little at a loss what next to look at. I don’t think replacing the sensor for the third time does any good. Any ideas and suggestions would be much appreciated.
By the way, the car has about 308K miles on it.