Could it be the MIL on OBDII mercedes be triggered by checking Emissions Monitor status with a handheld scanner?

Ok, here's a weird one:

Over the last week I've been chasing down a driveability problem my 96 C36 (M104) random stalling (turns out the MAF was the culprit FYI)

Got the car running flawlessly, decided to chase down some other things discovered including a burned out CEL (turns out the bulb was out- was reading codes off my Actron CP9175 scanner)

Of course, after replacement of the bulb, and still driving the car around to test to see if the random stalling has gone away. Car was perfectly fine drive - wise.-

During this time I'm monitoring the readiness status of the various emissions systems over the last 3k miles I've changed so many sensors I wanted to make sure everything was working as it should.

The MIL came on during driving around-scanning for actual codes produced a PASS NO CODES FOUND.

Been chasing this issue for the last 3 days, the CEL eventually shut off when I turned the car on without starting and let it sit in run. Of course, During this time I was checking status and scanning for codes and it would flip on.

I finally got it to shut off yesterday and didn't have the scanner plugged in. went for a 45 minute drive today and while sitting in a Starbucks drive thru decided to plug the thing back in -

In the back of my mind I was thinking about Murphy's law and how the MIL was going to pop up while I scan and I sure as hell was right.

- checking for codes got a PASS- no codes found

- checking Monitor status, I looked down and checked values, looked up at my dash and sure enough, MIL was staring straight at me.

Unplugged my scanner, shut car off, turned key to run and let it sit there and the MIL shut off (approx 15 seconds)

As an experiment, I plugged my scanner in again, and went to check monitor status and sure enough, MIL again.

Shut car off, turn to run, repeat and it's off again.

5x I did this.

So, could the MIL coming on after plugging in the scanner and checking monitor just be a test to show the light is working? Once again the only way it shuts off is if you put the car to run and let it sit there then it shuts off on it's own.

Of course, the light stays off if the scanner is unplugged and i'm minding my own business.

Anyone out there experience this? If this is the case, I've been chasing my own tail for 4 days now..

rjp

__________________
03 540I (GAK!!)
81 280E (W123)
70 LeMans Sport with pissed off Poncho 462"
1989 Silverado Step Side (under the knife- complete restomod)

Someone in another forum claims when he went to the local smog station in his 96 W202 the smog guy said there's a notice from CARB stating the 96 model years suffer from false MIL indicators.

Which could explain why mine had a bad bulb installed- if they can automatically turn you away cuz the MIL is on, at least if it's dead they are forced to plug it in to test it.

Around here if you fail smog they require you spend money on the car. A dead MIL bulb could save you money in this case.

I just put the dead bulb back in. I can only imagine them testing this car at smog and the MIL goes on because of them accessing the CPU.

that would suck.

rjp

__________________
03 540I (GAK!!)
81 280E (W123)
70 LeMans Sport with pissed off Poncho 462"
1989 Silverado Step Side (under the knife- complete restomod)