Driver side upstream O2 heater problem. Replaced the sensor. Still get the code. I assume it must be a problem prior to the sensor. Any suggestions?
Since you already swapped it out, you MAY have a wiring issue.
P0155 P0135 Diagnosing O2 Sensor Heater circuit, heated oxygen sensor - YouTube
Long tubes, right? They can lengthen the time for the heaters to work and that can help this. (o2 transport delay and front o2 heater duty cycle)
bj
Yep, long tubes. FWIW I just had engine rebuilt and installed DivisionX fuel rails.
IT's the stuff in the tune 99% of the time.
bj