Technical Definition:

Secondary Air Injection System Incorrect Flow Detected

Trouble Code: P0411
Address: 0x0411
System: Powertrain
Subsystem: Auxiliary Emission Controls
Technical Description:

Secondary Air Injection is an emission control that uses an air pump (either electric or turned by the drive belt) to move fresh air into the exhaust manifold(s) or exhaust ports when the engine is in open loop and pre-catalytic converter when in closed loop. This reduces hydrocarbon emissions (HC), Carbon Monoxide (CO), and oxides of Nitrogen (NOx). This fresh air helps convert Carbon Monoxide (CO) into Carbon Dioxide (CO2) and Hydrocarbons (HC) into water vapor (H20).

Possible Causes:
  • Damaged or missing check valve
  • AIR pump intake port plugged/damaged
  • AIR pump clutch malfunction
  • Holes or damage to exhaust components

Possible Symptoms:
  • MIL (Malfunction Indicator Lamp) illumination
  • Backfiring in the exhaust under hard acceleration
  • Engine running rich (This is counter-intuitive. See explanation below)
  • Squealing belt

Secondary Air Injection System Incorrect Flow Detected

Possible Solutions:

OBD-II Trouble Code Type:

Diagnostic Step:

Tech Notes:

– Faulty Vacuum hoses damaged
– Faulty Air Pump inoperative
– Air bypass solenoid harness is open or shorted
– Air bypass solenoid circuit poor electrical connection
– Air bypass solenoid leaking/blocked or stuck open/closed
– Air diverter valve leaking/blocked or stuck open/closed

Specific Makes:

– Engine hesitation

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