P0412

Symptoms

• Check Engine Light Is On
• Increased CO and HC emissions during cold start
• Emissions inspection failure
• Noise or whistle when starting the engine (if the valve is stuck)
• Otherwise the engine runs fine

Causes

• Faulty AIR A solenoid switch valve
• Open or shorted valve wiring
• Damaged or oxidized valve connector
• Faulty secondary air pump
• Clogged hoses or tubes of the AIR system
• AIR pump relay malfunction
• ECU malfunction (rare)

How to Fix

1. Read all error codes with a diagnostic scanner
2. Check the power supply and grounding of the AIR A switch valve connector
3. Check the integrity of the wiring from the computer to the valve
4. Measure the valve solenoid winding resistance (usually 20-30 ohms)
5. Check the operation of the AIR pump relay
6. Inspect the hoses and tubes of the system for clogging and cracks
7. Replace switching valve A if fault is confirmed
8. Reset the code and do a cold start to check

Related codes

Error P0412 by Vehicle Brand