The O2 sensor in my gf's 96 Sentra 1.6 L has an orange/brown discoloration on one side of the tip that samples the exhaust stream. Is this normal? Or does it indicate improper combustion? She is using a lot of coolant, whichh I think is being burned in the engine, since I can't find any external leaks.
She is getting the 0303 MIL code for O2 sensor, but I think the exhaust stream might be to blame, not the O2 sensor itself, since the exhaust has the effluent of the burning coolant.
Caprice I would look at another source for your info or you'll be chasing your tail on this. I double checked this code in two books and on one CD and they all say CYL, misfire for all Nissan Sentra, Altima, Maxima, etc. The O2 sensor codes start at P01xx in my sources. This is for years
The confusion lies in the fact that noone here is familiar with Nissan's MIL based flash codes. They are in use even on the early OBDII products. You did get this code by turning the ECM screw right, then left with the ignition on, then watching the MIL flashes, correct? It should have flashed long 3 times (03) then flashed short 3 times (03) for a result of 0303. *P0303* is a SAE standardized code for cylinder 3 misfire which isn't relevant in your case.
Flash code 0303 indicates a slow or dead front O2 sensor. The sensor has most likely failed. I looked at a wiring diagram and was surprised to find that this is a titania sensor (based on the schematic). I didn't know they used these post-OBDI. I would suspect that the white wire (check wire colors at the vehicle harnass, not the O2 sensor harnass) is where you would check with a digital voltmeter for varying voltage, with engine running and hot.
Any voltage range can be employed with a titania sensor, but I think Nissan likes to use 0-1 volt. The resulting voltage fluctuation should mimmic the much more common zirconia O2 sensor. I suspect you will find the output wire to have near zero volts -or- fluctuate very slowly.
BTW, if you have access to a simple OBDII scan tool that can display live data, that's the easiest way to start your O2 sensor check. You can see what the ECM sees, albeit at a slower rate than with a DVOM.
Comboverfish, I'm glad to learn this difference! So if I understand you right, your saying that the MIL codes are not the same as what you would see with a scantool? I guess what I'm asking is Nissan standard ISO 9141? protocol or is there just a difference between the code for the MIL *0303* and a scantool would display a P01xx for the O2 sensor?
This Nissan and some Nissans circa the early OBDII changeover in 1995 are capable of both methods. The OBDII connector is right under the dash, or you can pull off the center console trim and access the ECM mode screw like on older Nissans. The difference is that Nissan went to confusing four digit codes in 1996 that look an awful lot like SAE codes while not correlating to them at all.
Thanks for the confirmation of the 0303 code's meaning. Yes, I turn the screw to get the flash codes. Three long, three short. I don't have access to a scan tool.
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