Hi there, Nico club! I am the proud owner of a 2003 M45, and for anyone wondering if they should ever get one, it is worth mentioning (in my opinion) I absolutely adore this car. From the outside, it is a very sleek, car with amazing curves and beautifully crafted edges. Inside, a 340HP V8 powerhouse; the VK45DE.
As well as this rare gem has treated me, I have recently run into a problem.
The dreaded CEL, (or Service Engine Soon in the case of this car) light has popped on, reading error code "P0051".
I have researched this, (I do not know if the general information I have put together is true for this vehicle as well) but based on this knowledge, the code means:

P0051 OBD-II Trouble Code: HO2S Heater Control Circuit Low (Bank 2 Sensor 1).

The car has no symptoms except:
- Running rich.
- Slightly lower fuel economy (14.5 mpg, should be 17mpg) :-(
- Gas pedal has to be barely pressed in for start-up, not always, but occasionally. The start-up is not rough, though.
- Exhaust pipe on passenger side seems to be colder in certain areas, only after the first set of cats (felt by hand)
- RPMs slightly higher on cold start, returns to normal after heating up.

There are no other symptoms. The cars idle does not feel rough and is stable, drivability seems to have no changes, does not stutter or lurch forward during driving. No holes in the exhaust pipe (that I can see) or strange noises.
I take excellent care of the vehicle and maintain it in proper intervals.

Some remedies to fix this are:

Replacing bank 2 sensor 1 (this would be upstream passenger side, correct?)
Fixing the connection issues and reattaching the connectors
Repairing any open or shorted wiring
Replacing the heater circuit fuse
Replacing the ECM.

I have picked up a new sensor (Bosch brand, as true OEM sensors have been difficult to locate, and I have used Bosch sensors with no issue on other vehicles [have not used on Nissan/Infiniti yet]) hoping to remedy the issue.

My question is: after installing the new sensor, is there anything else I need to do or is it plug and play?
I am limited on tools, and I do not have further analysis tools such as a Scan tool or OBDII code reader.
I have looked on YouTube, in the manual, and online attempting to find information on how to finalize the process after install of the new sensor, to no avail.
Will I need to reset the codes via OBDII to get the new O2 sensor to produce original/desired functionality?
Is there anyone with experience changing these sensors on the 03-04 Model M45? I understand later generation M45 models us the same engine, possibly the same HO2 sensors. Maybe there is someone with some insight on what the process was for them?
Any help is greatly appreciated.
Thanks, NICOclub!

Hello
I have copied your discussion to the M45 and M35 forum as well. There you will get more pointed advice as well as answers to your questions if you search directly and don't need to wait for members to respond.

To answer your questions; generally no, you do not need to reset anything after replacing the sensor. The check engine light should promptly go away on its own if that was the problem, but if you disconnect your battery in the process of doing the work, then you will erase your codes anyway... and the car will correct itself and stop running rich.
But it really is as simple as it seems:
- buy/borrow oxygen sensor socket from auto parts store
- disconnect harness - remove old sensor
- apply antiseize carefully on new sensor
- reinstall sensor
- reconnect harness.