Hi guys,

I'm here because I've ran into a strange problem with the 06 350z (touring) that I own, and hope that other owners may be able to shed some light on exactly what's going on.

Just last week on a drive home my CEL suddenly came on and as I checked it the next morning (at a friend's) he informed me that it was BOTH of my header/upstream o2 sensors tripping the CEL, however he proceeded to check the air/fuel ratio to see if the sensors were still operating. And to my surprise the sensors were reading the ratios properly, the code had told us that the sensor's got trouble warming up, so at this point we are assuming it is an electrical issue related to the sensor's ability to warm up during a start. Knowing this now, we are going to attempt to check the o2 wires under an ohmmeter in order to test and see if somehow the wires are somewhat damaged.

What I'm afraid of is just having the replaced sensors and then running into the exact same issue not far down the road, as I'd like to fix whatever caused this issue in the first place (so I don't end up burning through o2 sensors while whatever's causing this problem still is around).

Some other information that may be helpful:

-I believe my car does not actually have o2 sensors, instead it uses air/fuel sensors.

-The most recent mod I have done on my car was replaced the cats with a test pipe and used an angled spark plug non fouler to have the post cat/downstream sensor sit outside of the test pipes.

-I also have a grounding kit and a voltage stabilizer currently installed on the car.

I apologize for not posting the codes as I did not write then down when we initially scanned it at my friend's house. I'll post em up once I go back the next time to check the sensor's wires with the ohmmeter.

Any response is greatly appreciated!! Thanks for reading!

 

test pipes cause CEL's

put your cats back on and the CEL will go away. otherwise, dont worry about it.

 

Yeah, I'm positive it's not the test pipes because the sensors that are currently triggering the CEL is the upstream bank 1 and bank 2 primary sensors. not the post cat downstream sensors plus I made sure that the post cat sensors are sitting well out of the test pipes, and they haven't triggered anything for the last 5 months when I've been driving with them.

I believe the 03-05 z's only have 2 o2 sensors as opposed to the 06+ which comes with 4 so it may be a little bit different

 

OP what were the codes? PXXX?

 

The codes were:
-P2A00 O2 Sensor Circuit Range/Performance Bank 1 Sensor 1
-P2A03 O2 Sensor Circuit Range/Performance Bank 2 Sensor 1

sorry it took so long for me to get back to this thread, I've been busy with Christmas n all lately.

 

Check for leaks off of the test pipe. I'm dealing with this code too.

Did you reuse gaskets or put in new ones?

 

Okay will do, I bought all new gaskets. Good quality stuff too but I'll have a look again when I have time. By the way I'm just wondering out of curiosity, but whats your fuel consumption like before/after the test pipes? Assuming you've got em on instead of cats as well?

 

I would suggest running some hfcs instead.

 

cats or test pipes... to each their own... i have pipes but i have also been tuned. if it is the upstream ones maybe it is because you are running leaner since the TP install..... just spitting out things.. not positive

 

^Good point, I would look at the live data if It were me.

 

with TP remember you will no longer have the back pressure that cats have

 

Breathing mods will make you lean, all it takes on a titan is a set of headers.

 

I looked at the live data with my scan tool, there didn't seem to be anything wrong with the air/fuel ratio. That's also how I know my upstream o2 sensors (the ones that are currently tripping the CEL) are still operational. My friend said it was the o2 sensors ability to warm up that's causing the CEL to come on, either it's the elements inside the o2 sensors that are busted, or the wires are just not conducting and transferring electricity properly to the o2 sensors.

the puzzling part is that BOTH of these o2 sensors went out at the exact same time, tripping the CEL, I'm inclined to think that there's a problem else-where which is causing both o2 sensors to malfunction like this.


edit: I checked and there were no leaks in and out/around the test pipes. Everything's sealed, including the spark plug non-foulers connected to the test pipe.

 

so do basic process of elimination and replace em........

 

So you watched the sensors' voltage go up and down while you drove the car?
It couldn't hurt to replace the 2 sensors anyway, but I doubt they're both broken. I think your car is running lean, and the sensors are trying to tell you that.

 

03 until i think 04.5 had 2 narrow band O2 sensors post cat and 2 wideband O2 sensors in the headers. They are all o2 sensors which are the same as air/fuel. Wide and narrow describes their sensing characteristics.

Check for a fuse for the heater circuit.