Diagnostic trouble code (DTC) P1411
indicates a problem with the Secondary Air Injection (SAI) system, which is part of the vehicle's emissions controls. The specific definition of this code can vary by vehicle manufacturer. For some European models, it often means the secondary air injection system has an "implausible signal" or insufficient flow detected on a specific engine bank. On many Chrysler, Dodge, and Jeep vehicles with a Multi-Displacement System (MDS), the P1411 code points to a fault in a solenoid that controls the cylinder deactivation. 
Common P1411 causes
The cause of a P1411 code depends on the specific vehicle and its corresponding system.
For secondary air injection systems (e.g., Porsche, Audi):
- Failed air injection pump: The electric pump responsible for pushing air into the exhaust might have failed mechanically or electrically.
- Faulty combi valve: Also called a changeover or check valve, this valve directs the air from the pump into the exhaust. If it's stuck closed, no air can get through.
- Vacuum leaks: The SAI system is often controlled by vacuum. A leak in the vacuum lines, reservoir, or related solenoids can prevent the SAI valve from opening.
- Clogged hoses: Blockages in the air supply lines between the pump and the check valve will prevent airflow.
- Electrical issues: Problems with the wiring harness, fuses, or relay for the air pump can trigger the code.
For cylinder deactivation systems (e.g., Dodge, Chrysler Hemi):
- Faulty MDS solenoid: A problem with the solenoid that controls cylinder reactivation can prevent the proper operation of the displacement system, triggering the code.
- Low or dirty engine oil: Insufficient or contaminated oil can cause problems with the MDS solenoid and lifters.
- Damaged lifters or valve springs: Wear or failure of the hydraulic valve lifters or valve springs can be a symptom of an underlying issue causing the P1411 and related misfire codes.
- Wiring problems: Electrical shorts, corrosion, or open circuits in the wiring harness connecting to the MDS solenoids can cause a malfunction.
Symptoms of P1411
The symptoms you experience will depend on the underlying cause, especially whether the code relates to the SAI system or the MDS.
- Illuminated check engine light: This is the most common and certain symptom.
- Engine misfire: When P1411 is paired with a misfire code like P0301, the engine can experience a shake or rough idle.
- Rough idle or performance loss: A malfunctioning SAI or MDS system can lead to a rough idle, poor acceleration, and reduced performance.
- Engine knocking noise: In Hemi engines, a fault in the MDS system can cause a knocking sound, often from the right side of the engine.
How to diagnose and fix P1411
The repair process depends heavily on your vehicle and the source of the problem. A diagnostic scanner is necessary to confirm the code and check for other related codes.
For SAI systems:
- Check fuses: Start with the basics by checking the fuse for the secondary air injection pump.
- Inspect vacuum lines: Look for any cracked, disconnected, or collapsed vacuum hoses or connections. Perform a vacuum leak test if necessary.
- Test system components: Using a scan tool, you can activate the air pump and related solenoid valves to confirm they are working correctly.
- Inspect for clogs: Check the hoses and valves for any physical blockages that could restrict airflow.
- Test electrical circuits: If necessary, test the wiring harness and relay for the pump to rule out electrical faults.
For MDS systems (Dodge/Chrysler Hemi):
- Check engine oil: Ensure the engine oil is at the proper level and clean, as low or dirty oil can impact MDS function.
- Inspect solenoid and wiring: Locate and inspect the MDS solenoid and its electrical connector for damage, corrosion, or loose wires. You can sometimes diagnose a faulty solenoid with an ohmmeter.
- Diagnose related issues: If there is a misfire, swap the spark plug or coil to see if the issue moves. A compression test on the affected cylinder can help determine if there is an internal engine problem like a bad lifter or valve.
- Disconnect the MDS connector: For diagnosis, some mechanics may temporarily disconnect the MDS solenoid connector. If the engine runs smoothly with it unplugged, it points to an issue with the solenoid or its electrical circuit.
