Drive with caution — fix soon.
This code means the engine computer detected that the secondary air injection system isn't moving the right amount of air, which is the fresh air pumped into the exhaust at startup to cut emissions. It usually points to a faulty air pump, a stuck or leaking switching valve, or clogged passages and hoses. It's a fairly common code and is usually fixable without major engine work.
$200 – $700
Varies by vehicle and root cause.
Usually yes, since the secondary air system mostly affects cold-start emissions and not everyday driveability. The car stays safe to drive, but it will likely fail an emissions test and run dirtier when cold, so plan to have it repaired.
Most repairs run between about $200 and $700. Cleaning passages or replacing a switching valve is cheaper, while a new secondary air injection pump pushes the cost toward the higher end.
It's not a safety emergency and won't typically leave you stranded, but it does mean your emissions system isn't working properly. It should be repaired so the car passes emissions and doesn't pollute more than necessary.
It's a pump and valve setup that pushes fresh air into the exhaust during cold starts to help the catalytic converter heat up and burn off pollutants faster. A P0412 means the computer detected the airflow wasn't what it expected.