OBD-II code · Powertrain (generic)
P0411 Secondary Air Injection System Incorrect Flow
When the ECU commands secondary air injection, the actual flow measured by the front oxygen sensor (or a dedicated mass flow meter) does not match the expected value. Usually a partially blocked passage or a leaking combi valve.
Is it safe to drive with P0411?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyAir passages in cylinder head clogged with carbon
- PossibleAir pump weak
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 1–6 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Secondary Air Pump, Secondary Air Valve, Secondary Air Passages
Related codes
- P0410Secondary Air Injection System Malfunction
- P040EEGR Temperature Sensor A Circuit Intermittent/Erratic
- P040FEGR Temperature Sensor A/B Correlation
- P0412Secondary Air Injection System Switching Valve A Circuit
- P0413Secondary Air Injection System Switching Valve A Circuit Open
- P0414Secondary Air Injection System Switching Valve "A" Circuit Shorted
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.