The data protocols may be standard, but (as you mentioned,) the hardware interfaces are different (and not just the "Big 3" - aren't Toyota, Honda, and Nissan also on different hardware bus standards?)
You're right. I checked and there is CAN, ISO, KWP, VPW, and PWM. Starting in 2008, cars sold in the US will be required to use the CAN bus interface (actually a varient of CAN). http://en.wikipedia.org/wiki/OBD-II.
Excellent. Maybe now that we're standardising the data stream, we can begin to standardise the data SOURCES, and cut down on the part numbers needed. I thought that was what standardisation was...
Umm, so there are only 2 O2 sensors right? I'm getting the code saying that bank one sensor two has high voltage. That means the sensor sticking out of my cat right?
Umm, so there are only 2 O2 sensors right? I'm getting the code saying that bank one sensor two has high voltage. That means the sensor sticking out of my cat right?
To answer the question about the size of the O2 sensors. It would be 7/8" or its metric equivolent of 22mm for 90% of the vehicles out there. A lot of the other 10% are Toyotas and will probably ise 2 studs with 12mm nuts holding them in place. 5-90 is right that the newer WHEGO sensors are more accurate than the old HEGO sensors which are better than the reaaly old EGO. You remember the old 1 wire ones that cost all of $20. Honda and Toyota are 2 OEMs using WHEGO sensors, but they call them Air/Fuel Ratio Sensors instead of osygen sensors and they cost a ton. Some of the people that are involved in writing the laws concerning emissions laws and regulations due know what they are talking about. My instructor for my Emissions License had a lot to due with PA's Enhanced Emissions Inspection Certifacation program. He gave me a great tip that I will share with you guys. On a lot of newer(OBD-II) vehicles when you have a P0420 Catalyst Efficiency code present there are two primary causes that are not the cat and they cover 95% of the vehicles. Make sure there is no exhaust leak present because it will give a false reading and secondly change the downstream O2 sensor as it at the end of its service life and is giving a false reading. Has not been wrong about it in over 30 changes of O2 sensors so far. Finally, scanners are great. I use Modis myself, but they are only as smart as the monkey operating it.