P0411
Secondary Air Injection System Incorrect Flow Detected
If your code reader dashboard displays the generic DTC error code P0411, your vehicle is currently experiencing an active failure related to "Secondary Air Injection System Incorrect Flow Detected". Proper system troubleshooting is required to safely clear this warning.
Driver's Summary
P0411 is triggered when the PCM detects an abnormal condition associated with secondary air injection system incorrect flow detected. Typical symptoms include check engine light, failed emissions test. You can continue normal driving, but schedule an inspection at your next service appointment to clear this code properly.
Symptoms
Check engine light, failed emissions test
Common Causes
- Failed air injection pump
- Clogged air injection ports
- Faulty check valve
- Vacuum leak at control solenoid
How to Fix
- 1 Replace secondary air pump
- 2 Clean carbon from injection ports
- 3 Replace air injection check valve
- 4 Fix vacuum leaks
Technical Explanation
Code P0411 is confirmed when the ECM's diagnostic algorithm detects a parameter deviation that persists across a defined number of consecutive drive cycles. EGR flow is verified by monitoring changes in MAP sensor readings before and after valve actuation; correct EGR flow produces a predictable pressure drop in the intake manifold that the ECM can measure with precision. The MIL illuminates after the fault is confirmed on two consecutive drive cycles, and the freeze frame data captured at first detection is stored in the PCM's memory for diagnostic reference.
Is It Safe to Drive?
This code won't strand you, but it shouldn't be ignored indefinitely. The failed air injection pump issue identified by P0411 can mask other developing problems and will cause an automatic emissions test failure in most states.
Mechanic's Pro Tip
For P0411, test the solenoid's coil resistance with a multimeter before ordering parts — most solenoids should read between 14 and 40 ohms; an open (infinite resistance) or short (near zero) confirms it's failed electrically. Also verify the PCM is commanding the solenoid by backprobing the connector with a test light during the relevant operating condition — if there's no command signal, the fault is in the PCM or wiring, not the solenoid itself.
Check valve: $80 - $150; Air pump: $200 - $500