P0411 - SECONDARY AIR INJECTION SYSTEM - INCORRECT FLOW DETECTED

Secondary air injection is an emission control system. It uses an air pump to move fresh air to the exhaust manifold when the engine is in open loop and to the catalytic converter when the engine is in a closed-loop. This achieves a reduction in hydrocarbon, carbon monoxide, carbon dioxide, and hydrocarbon emissions.  A check valve is located in the air supply line; thus, it prevents the entry of exhaust gases into the pump.

The check valve, which rules the airflow, might be be vacuum controlled or electrically. When the PCM (Powertrain Control Module) activates this valve, the vacuum moves to the check valve so that it opens and fresh air flows.

During acceleration, the air pump is deactivated, thus avoiding shots in the exhaust. Therefore, the PCM activates the secondary air system to send fresh air to the exhaust system. Because the Oxygen (O2) Sensors translate this fresh air into a lean condition, fuel settings soon begin to move in the direction needed to compensate. The Powertrain Control Module (PCM) waits for this to happen in a short period during the self-test. If the PCM sees that the fuel trim does not increase in a short time, it interprets this as a malfunction in the air injection system and the diagnostic code P0411 OBDII is set.

• Check Engine Lighting.
• Hesitation at the time of acceleration.

When the DTC code P0411 OBD2 is set, it means that some of these problems have occurred:

• The check valve may be defective.
• The air pump intake port may be blocked or defective.
• Air pump clutch failure.
• Holes in the exhaus

The steps to follow for the respective diagnosis and subsequent repair of the fault code P0411 OBD2 are

• With the key in the ignition position and the engine off, use an automotive scanner with which you will control the pump. It must be activated. If not, disconnect the air pump relay and check to see if it is affected by the high temperatures. Repair or replace as necessary.
• Checks the battery voltage in the switched battery supply to the relay and the relay control circuit. If there is no voltage in any of these components, there may be faulty fuses or bad cables. Proceed to repair or replace.
• If voltage is present in both components, use a fused jumper, to connect the battery power to the air pump power circuit. After doing so, the pump should activate. If not, you must check that there are power and ground in the air pump at the time it is bridged. If no voltage or ground is present, you must check the wires leading to the air pump. But if the voltage and ground level is OK, you must change the air pump, repair or replace it.
• Change the air pump relay.