Straight from the TX gov:
...So if you have a ford or chevy with 9 monitors, 8 have to be ready if you have a brand new german car with 100 sensors, 99 have to be ready - how stupid is that..... "1 not ready" is a stupid criteria. My old '95 only had 2 sensors - so "none" ready would have passed...
OK, Brain75 is overthinking monitors.
When we refer to monitors, we're referring to the software processes in the ECU (PCM, etc) that are monitoring (testing) emissions control functions on 1996 and newer OBDII certified vehicles. The following systems are monitored:
Comprehensive components (Opens and shorts, etc),
Secondary air injection,
Add or subtract as necessary, but it comes down to no more than about nine monitors on even the most complex system. In theory, there can also be an AC monitor, and a heated catalyst monitor, but I can't say that I've ever seen either.
A monitor should not be confused with sensor, nor does each sensor have its own monitor. For example, there is no crankshaft position sensor monitor, or throttle position sensor monitor. A fault with one of those sensors might be detected by the comprehensive component monitor.
Brain75, your old '95 has less to do with any of this than your German car's '99 sensors'. While some 1995 and older vehicles have elements of OBD II, the mandate did not go into effect until the 1996 model year. As far as I know, no emissions testing program is testing monitors on 1995 or older vehicles. Definitely not California.
I can also assure you that your old '95 came equipped with more than two sensors. Off the top of my head, I'd guess MAF, TPS, ECT, IAT, CKP, CMP, O2, maybe a MAP sensor, and probably more.
In California (Btw, everything at justsmogs.com should be considered specific to California):
Model year 2000 and newer gasoline powered vehicles (Including hybrids), all monitors, with the exception of the evap monitor, must be complete. In other words, you can pass with an incomplete evap monitor, but everything else must be complete.
Model year 1999 and older gasoline powered vehicles you can pass with any one monitor incomplete (Doesn't matter which one), but no more than one incomplete monitor. This even applies to a 99 sensor German car and a two sensor Chevy.
All monitors must be complete on model year 1998 - 2006 diesels.
Model year 2007 and newer diesels are allowed two incomplete monitors. Any two, so mix and match.
That said, if any of the above monitors detects a problem with any sensor (Doesn't matter if there are 99 or two), a diagnostic trouble code will eventually be triggered (P0xxx, P1xxx, etc), the check engine light (MIL, service engine soon, etc) will come on, and the vehicle will not pass a smog inspection in the State of California (Probably not anywhere else) until the issue is repaired and the monitors are once again run to completion.
Hopefully that all makes sense.