All of the 1996 & later cars with ODB2 must pass a "ready" test. All of the systems must have performed their tests!
The most common problem is "tired" oxygen sensors that still work BUT aren't up to par as far as passing the ready test. ASK the testing station if the car failed the READY test. IF so ask what systems HAVEN'T been tested.
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)