I looked in all the fuse boxes and can't find a fuse or relay for the O2 sensor heater. It's throwing a code that tells me the O2 sensors are not heating up. Internet says there is supposed to be a fuse and maybe a relay I cannot find either one. 3.0 has two O2 sensors both have two White wires a Black and a Grey. The two white wires are supposed to be the heater circuit.
Both O2 sensors have been replaced and are new.

 

Bank 1, sensor 1 and bank 2, sensor 2 are fused on engine cntl 3 fuse
Bank 1, sensor 2 and bank 2, sensor 1 are fused on engine cntl 1 fuse
Both are in the underhood fuse block.
What year and what codes? I have 2002 factory service manuals.

 

I doubt you have fuse problems because those two fuses power several sensors as well as the ecm. I am looking at the grounds now.

 

The ecm pulses grounds to each oxygen sensor and looks at voltage feedback to determine whether they are working properly or not.

The 3.0L Saturn L has four oxygen sensors, two upstream to control mixture and two downstream to monitor cat efficiency.

 

I had a similar issue a few years ago.
Replaced the O2 sensor, still had a heater circuit fault.
Upon inspection I discovered the heater circuit pin had pushed back in the harness connection to the sensor.
Ended up direct wiring the sensor. No problems since.

 

Should I unplug the O2 sensor? isolate the white wires and try to read the voltage to the sensor. If I find no Voltage Then What? If I take a continuity tester, should I check each individually to ground on the body? or go to negative on the battery? Once finding which is negative. Should I cut the other wire and feed it 12 volts from some other ignition on a 12-volt source thru an in-line 15 amp fuse?

 

In addition Codes P0139, P0159, P0140 & P0160, P0133, P0152, P0161, P0136 & P0156, P0031 & P0051 these 2 codes refer directly to the Heaters
Any additional help would be appreciated. I have until Nov.27 to find and repair this problem. The car shows many other codes but how many are being affected by the O2 sensors is unknown

 

Read post 4, what are your codes? This is a complicated system, do not add circuits or grounds. What year is your car?

 

Indeed please post all of the codes for your 2005 l300, specifying which engine you have.

Please list as Pxxxx as you did in your previous post

 

2005 only had the 3.0 v6. I will look up the codes listed but my manuals are for the 2000-2002 cars. The 2003-2005 cars are slightly different.