Quote:
Originally Posted by crystalworks
Both of these were 5 pin on the controller to body side. I got resistance on pins 3 & 4. Was the same on both the old and the "new" sensor. The sensor itself had 7 wires going to the control box.
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That's very possible that I got the pin count wrong, I was going off of memory.
In any case, I believe it's very very unlike that the controller is what goes bad. My suspicion is that is the actual catalyst element inside the probe that gets poisoned. The NOX sensor effectively works like a wideband O2 sensor with an added step. There's a catalyst inside the probe that takes NO and NO2 and brakes it down into N2 and O2. The sensor then measures the amount of O2 and calculate NOX. All the processing is done in the controller box that sends back to the DDE a processed signal via CANBUS. The DDE doesn't get a raw analog signal from the sensor, but a processed value from the controller.
It's my understanding that there's a baseline calibration done on each individual sensor that is uniquely paired to a controller. I think that's why they are not sold separately.
I'm not really sure there's a way to assess whether a sensor is "good" or "bad" without a known sample to test the reading against.