Check Engine Code
P0411
Secondary Air Injection System Incorrect Flow Detected
What P0411 means
The secondary air injection (SAI) system pumps fresh air into the exhaust right after cold start to help the catalyst light off faster. P0411 means the ECM isn't seeing the expected O2 response during that injection.
Symptoms
- Check engine light
- No drivability impact typically
- Emissions test fail
Likely causes (most common first)
- Failed secondary air pump
- Stuck or clogged combination valve (carbon buildup)
- Damaged hose/line to the exhaust
- Failed check valve
- Corroded electrical connection to the pump
Can I keep driving?
Low — mostly emissions/economy
Typical repair cost
DIY fixes can start near $100 (parts only). Shop repairs for P0411 typically run up to $900 depending on the underlying cause and vehicle. Start with the most common cause — Failed secondary air pump — before throwing parts at it.
Recommended parts & tools for P0411
Our buyer’s guides cover the tools and parts that pair with AXLY:
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