What is the fault code P0491? What is Secondary Air Injection System Insufficiently Flow Bank 1 fault description. How do I fix the P0491 fault code What are the causes and symptoms of the P0491 error code?
What is the P0491 fault code? What does it all mean?
Modern vehicles have a multitude of systems that work together to reduce emissions. The critical emissions system in many vehicles is the secondary air injector (SAI / Secondary Injection) system. If the powertrain controller module (PCM) detects a low airflow in the secondary injection system, P0491 is recorded. The code description refers to the engine bank that contains the first cylinder.
The SAI system supplies the air required for the oxidation process within the catalytic converter or exhaust manifold. This system is also known as “AIR” Air injection reaction is also known as
An air pump drives the SAI system’s engine’s drivebelt (old vehicles) and an external electric motor(new vehicles). The pump’s airflow is directed to either the catalytic converter (old vehicles) or the exhaust manifold (new vehicles). This aids in the reduction of harmful exhaust gases. Some solenoid-operated valves are controlled by the PCM to control the airflow from pump. If the secondary airflow for a given time is low, the PCM will trigger the P0491 code.
The P0491 fault code can affect vehicles such as the BMW 745i, Audi, Volkswagen, Seat and Mercury, Smart, Dodge, and other Ford models.
What causes the P0491 Fault code?
Here are some reasons why P0491 should be set.
- – Fuse or air injection pump malfunction
- – Check valve on defective exhaust manifold
- – Sensor circuit problems, such as loose or damaged connections or wires that are bent.
- – Vacuum hoses and air hoses that leak
- – Defective vacuum control switch
- – A malfunctioning system relay
- – Defective secondary pressure sensor
- – A defective bypass valve or diverter device
- – Blockage of secondary air injection port
What are the symptoms of the P0491 Malfunction code?
You may experience the following symptoms if your vehicle has the code P0491:
- – Illumination at the check engine lights
- – No power during acceleration
- – Vehicle stalling during idling, or when it starts
- – A hissing sound coming from the air injection system (signal of a vacuum leak).
- You may occasionally hear unusual noises coming from your air pump.
- – Triggering other fault codes
How to Fix the P0491 Fault Code
- – Replacing damaged cables and connectors.
- – Replacing the secondary air injection pump
- – Replace the one-way check valve in the pump
- Vacuum leakage? Repair or replace the damaged fittings or vacuum hoses
- – Replacing the pump fuse
- – Clean the head of the cylinder
V-configuration engines have dual inlet ports, which means double check valves. To ensure that air flows in one direction, you should inspect both valves.
Recurrent pump failure can occur if the secondary air injection pump pump is not replaced with the check valves. All components must be examined.
How Serious Is the P0491 Fault Coding?
The severity level of the P0491 code depends on what symptoms are present in the vehicle. The vehicle may stall while it is being driven. This can be dangerous. A malfunction in the secondary injection system can lead to increased emissions. It is best to correct the issue as soon as possible.
