1998 Maxima SE auto. 150k miles.

I just got this car in April 2017.

SES light.

Checked codes, here is what I got:

P0325 0304 KNOCK SEN/CIRCUIT
P0154 0509 FRONT O2 SENSOR-B2

I Replaced knock sensor and front 02 Sensor-B2 (The one closest to the front of the car radiator. Standing on the left side of car (The side with the transmission) looking at drivers side door, it's the 02 sensor on my left aka closest to font of car.

Ok so I replaced both the knock sensor & front o2 sensor-B2. Reset ecu codes (Screwdriver in side of ecu).

Sure runs WAY better (wow. Can smoke the wheels from a dead stop. Could not do that before. I'm assuming due to the new knock sensor) BUT 1 day later SES light came on. Still runs GREAT but - checked codes and this time it's only the P0154 0509 FRONT O2 SENSOR-B2. But why? I just replaced the front 02 B2 sensor.
OK, thought maybe sight chance of defective sensor, so I replaced the FRONT O2 SENSOR-B2 again, cleared the codes and one day later same thing. SES light came on - check codes: same things. P0154 0509 FRONT O2 SENSOR-B2



Is there any possibility I'm replacing the wrong 02 sensor? Is it possible that the P0133 0409 FRONT O2 SENSOR-B1 is bad but I'm getting a code for the B2 sensor?? I find it highly unlikely to have 2 new defective 02 sensors. Something else must be wrong.

Any suggestions? I have another new 02 Sensor, I'm tempted to replace the B1 sensor to see if anything happens.

Thanks

Make sure that the oxy sensor fuse is intact, and sand till shiny. Fuse box by left knee, right side.

Jvg: Thanks for responding. Fuse is good, I checked continuity, no resistance or open circuit. I sanded the fuse blades as well.

Is there anything else I can try? I read somewhere else there as a guy that had a similar issue which cleared up simply by unplugging the ecu from the harness (down near the passenger side foot area) and plugging it back in.

I'm tempted to try this.

Thanks

The codes can be cleared either with a code reader, or by disconnecting the battery over night.

But if the problem still exists, the codes will reappear

Thanks. I already know how to read and clear the codes via the screw on the side of the ecu..

Just trying to figure out the issue so the problem resolves. To further detail the resolve I heard about - it sounds like from what I heard was that a similar issue to this was fixed by unplugging the ecu then plugging back in, not specifically doing so to clear the code but reseating the plug and making sure all terminals are contacting - to rule out the possibility of a loose connection at the ecu.

Any other ideas guys?

Thanks!

FINAL ANSWER:

I replaced the B1 (bank 1 right side. When standing on the drivers side of the car facing the transmission, its the one on the RIGHT closest to the firewall)

THIS FIXED MY ISSUE. That's right, the code I got was for P0154 0509 FRONT O2 SENSOR-B2 (LEFT SIDE CLOSEST TO RADIATOR) , BUT REPLACING THE RIGHT SIDE B1 FIXED THIS!

My Car is BACKWARDS!! The 02 sensor wires must be crossed somewhere, either in the harness or maybe crossed pins at the ecu connector.

-------> BOTTOM LINE <------ DON'T WASTE TIME IF YOU GET AN ERROR CODE FOR AN 02 SENSOR, JUST DO THE RIGHT THING AND REPLACE ALL 02 SENSORS AND REPLACE THE KNOCK SENSOR TOO. Chances are if an 02 sensor goes bad, it's probably old and the other 02 sensor(s) are probably old and lazy too. Just replace them and save the old ones to throw at your neighbor if he's too loud or annoying etc.