Rogue252

The model identification number on my VIN plate shows my car should be a Cali Spec(ugh) if I'm reading it right. 12th character is the region identifier right? Here's why I'm a little confused, though. I read here on the org that I should have 4 connectors right in front of my valve covers if its Cali. I have 3. I do have CEL on, P0325, P0325(yes I get it twice from Autozone?), and P0138. Knock Sensor Circuit(x2) and Heated Oxygen Sensor 2 Circuit High Voltage. Could the Heated O2 be thrown because its not hooked up at all?

DennisMik

iTrader: (2)

To start with, the 12th digit of the ID number (not the VIN) is the emissions code. N= Canada, U= US Federal and V= California.

But you don't fully understand what or how Nissan does the codes. Both the Federal and the California emissions can get a P0138, it is not exclusive to the California emissions cars. Nissan worked hard to try to keep the average guy from understanding it.

Click on this link ([url="http://boredmder.com/FSMs/Nissan/Maxima/1999/EC.pdf"Service manual section EC[/url]) and look at pages 219 and 249. They are both for code P0138, page 219 being for a California Emissions car and page 249 being for Federal emissions car.

As you have figured/found out, there a 3 oxygen sensors for a Federal emissions car and 4 oxygen sensors for a California emissions car. Now carefully look at the words on pages 219 and 249.
Page 219 says REAR Heated Oxygen Sensors.
Page 249 says REAR Heated Oxygen Sensor.

You have a Federal emissions car. To verify that, look for an oxygen sensor in the exhaust pipe after the catalytic converter. The catalytic converter is approximately under the front passenger seat and you have to look from the driver's side of the car. If you have a Federal emissions car, there will be an oxygen sensor behind the catalytic converter. If you have a California emissions car, there will not be an oxygen sensor behind the catalytic converter.

And one last tidbit. The P0325 knock sensor code shows up along with just about every other code. We call it a ghost code. Fix your other problem(s) and the knock sensor code goes away, too.

Rogue252

Seems there is a bracket of some sorts that hold the O2 sensor connectors right in front of the valve cover. Bracket on my B1S1 is gone, looks broken. It is however there, it just hangs loose near the radiator. That was the missing O2 sensor I wasn't finding. The car is in fact a Cali spec. 4 total sensors after all. Thanks for the help!