Failed Smog Test - S420 Benz 1996

Can anyone help?
My S420 Benz 1996, failed the smog test twice and my mechanic has informed me that he had checked all possible reasons the will cause the car to fail
the smog test . The print of the test shows "Not Ready" for all he 5 points. Today my mechanic told me that the dealer recommended that I'll replace the computer in my car inorder to pass the test. Is there anything else that can be done? Any comments.
Thanks, Shimon
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Prior to the test, was the battery dead or disconnected for some reason?
If so, the "monitors" in the engine computer must regain their "knowledge base" and that is done by driving the car for a week or so including at least 15 miles at 55 to 60 (not above) on the freeway. The monitors record the performance of the catalyst, air injection etc and need X number of driving cycles to accumulate sufficient information, dealer can tell you the exact driving cycle needed to satisfy that requirement.
I just went through this in Calif. Engine was fine but car failed due to insufficient number of valid monitors due to battery having been changed just before the SMOG test. Ten days later all monitors were valid and it passed.
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T.G. Lambach wrote:

Don't get me started about our bureaucrats and their f**ked up Smog Laws here in Calif. They're never happy except when passing regulations, figuring out new tests so the smog stations/mechanics need to buy another new $100,000 machine and then narowing the limits to get more cars to fail. Been chosen for this "test only" BS the last 3 times on my 2 cars. F**k em! The only good point, my '73 SL will never need another smog check
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Added thought: Calif. allows two monitors to be inactive so not all have to be in a "ready state". I believe there are five or six monitors.
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Computer are never at fault. I suggest you let the dealer check out the car. Independent rarely have proper tool to fully test out the car.
He probably asked several thousands of dollars to do the repair... No stinking way. He just want your money. Take car elsewhere to have it inspected.
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I had a similar problem when I disconnected my battery for repairs a week before I went in for the smog test. If your battery has been disconected (and thus the computer has been reset), you have to drive the car enough for the computer to have a chance to report and store any problem codes. If manufacturers didn't build in this requirement, many people would just disconnect their batteries to clear any possible bad codes before heading the testing station ;) Mercedes informed me that I needed to drive 100 miles after I disconnected the battery. They said normal driving was fine and did not tell me of any requirement for driving at any specific speeds for any specific period of time was required.
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As also seen by other responses, "Not Ready" is an indication, that the computer has not yet gained enough knowledge about the condition of the engine, possibly because it has been reset due to disconnected battery.
This "feature" was introduced on purpose to prevent reset of the computer as a means to pass the smog test, when engine is not in good enough condition.
Are you sure, that your mechanic knows what he is doing, and that he really spoke to the dealer?
I think it is quite unlikely, that the computer itself creates the problem.
And the computer is not cheap!
Shimon wrote:

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