2010 TDI Not passing Smog Inspection

I replaced a battery myself about 8 months ago, been driving since then just fine.

I brought in the car to the dealer after the check engine light came on. They narrowed the issue down to the DPF filter (took them 4 hours of labor to figure that out, not sure why it took so long).

After having the dealer fix that, I brought the car to the smog station. My smog failed because the computer monitors weren't registering (it looked like they were still flashing on the odbii check).

I was told that just 'driving it on the highway for 20 miles at 60mph' would normally reset those monitors.

I drove about 60 miles to be safe, and I'm still failing! Anyone has any insight into what could be the cause of this?

you probably have a few OBD readiness flags showing not ready. A few cold start to warm cycles usually clears them. Borrow a OBD scanner to make sure. Not sure how it is in CA but where I am more than 3 not ready/fail states means emissions failure.

After clearing codes, setting readiness typically requires a prescribed number of successful tests of the diagnostics systems to indicate the diagnostics are functional and working (i.e. "ready"). Usually this number is 3 "warmup cycles"that result in successful tests. The test conditions and number of successful test cycles required to show "ready" are specific to the platform and whatever the EPA bought off on for that particular ecu software version, but for many/most VW/audi they are: start the car with coolant temperature <40C, warm up at least 20C, and all readiness related emissions devices are tested as functional and able to show faults.

What this means for someone in this situation is: just drive the car and check it again in a few days.

at least one test will not complete until he car completes an active DPF regeneration cycle on its own.

could take a couple hundred miles.