Drive with caution — fix soon.
P0411 means the secondary air injection system, which pumps fresh air into the exhaust during cold starts to help the catalytic converter heat up and cut emissions, isn't flowing the correct amount of air. Common culprits are a stuck air switching valve, a failed air pump, or carbon and moisture clogging the system. It mainly affects cold-start emissions rather than everyday driving.
$150 – $600
Varies by vehicle and root cause.
Usually yes. The secondary air system mostly works during cold starts, so the car typically drives normally when warm. You may notice rough running when cold, and it will fail emissions, so get it checked soon.
It varies widely. A stuck valve clean or replacement can be $150-350, but a failed air pump is pricier, often $400-600 or more with parts and labor.
It's moderate. It won't usually leave you stranded and the engine generally runs fine warm, but it increases cold-start emissions and will fail a smog test, so it's worth repairing.
The most frequent causes are a stuck air switching valve and a failed air pump, often due to carbon or moisture clogging the system. Leaking hoses and a bad check valve are also common.