which oxygen sensor is the one that goes to the front engine?
I want to replace one that causes a gas leak.
Is there two that go in front of the engine or is it only one?
Also, how are they removed? is there a special tool for it. I don't want to use a special tool.

thanks

 

VQ35DE engine have
Two Primary 02 sensor: upstream, before the catalytic converter.
1 : near the firewall with blue wire
2: near the radiator with blue wire


Two Secondary O2 sensor: downstream, after the catalytic converter.
1. Near the radiator ( above it : Primary 02 sensor ) with red wire
2. Near the oil pan : with white wire.

Hook up your vehicle to OBD II scan tool to check for specific errors code.

 

None of them cause "gas leaks." If you have a bad primary sensor you can end up running a rich air/fuel ratio which causes excess gas consumption, but no leak. And yes, you'll need an O2 wrench to remove them unless you want to clip the wires and use a deep socket.

Are you getting a check engine light and code for an O2 sensor?

 

The only light I keep getting is P0455 and P0442 and I read in another thread that it was resolved by replacing the oxygen sensor. It kills my mileage but I have the P0507 one that I got to keep doing the relearn but no success.

 

Those 2 codes are not for O2 sensors.

P0442 and P0455 are both codes for the fuel tank cannot be vacuumized. Common cause is the gas tank cap loose, missing or defective. But any kind of a leak in the tubing for all the emissions stuff can also cause the codes.

Read the manual for the codes and start checking.
Page 359 for P0442.
Page 403 for P0455.

 

I tried everything. I changed the vapor canister, control valve,gas cap, vapor canister's/control valve hoses. what's next? the front sensor where the oxygen sensor connect?

 

I can't tell you a specific part. You could have a damaged metal line that got hit by a rock, you could have a rusted out fuel filler tube, the pressure sensor could be bad, lots of things. If you read the manual, you saw that they gave you a list as long as your arm. All I can say is keep working at it.

 

I suggest you first disconnect your battery overnight. It's possible that your trouble codes may go away - many of us solved our problems in this manner. Continue chasing your problem only if the codes/CEL persist even after disconnecting your battery.

 

It will go away but at some point it returns back. Sometimes, it turns off by itself but always comes back. I don't know what makes it do that.

 

The O2-related codes are set by thresholds that by Nissan's own admission are too tight (something like 5% deviation from the nominal value). So, whether this code gets set, or does not get set, depends on many things.

On my car (2000 SE), it was set twice during my 14 years of ownership:

• Once in cold weather and deep snow, with the sensor (and the cat) being enveloped in snow.
• Once in hot weather (90-100 degrees), when driving at high seeds (70+ mph) for extended periods of time (5+ hours).

In the first case, the CEL annoyed me for several months but then it went away on its own. By the time the second incident happened, I was smarter and cleared the light (and codes) by disconnecting the battery .

 

I've also tried disconnecting the battery overnight but it does clear for like a day.