P0494 Fault Code

Fan Speed Low

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0494 fault code indicates that the engine control module (ECM) has detected that the secondary air injection system's fan speed is too low. This system is designed to help reduce emissions during cold starts by injecting air into the exhaust stream to promote combustion. A low fan speed can hinder this process, potentially causing increased emissions and impacting engine performance.

What are the symptoms of the P0494 code?

Common symptoms associated with a P0494 fault code may include:

• Illuminated check engine light on the dashboard.
• Increased exhaust emissions, which might fail an emissions test.
• Noticeable drop in engine performance, especially during cold starts.
• Potential rough idling or stalling of the engine.

What causes the P0494 code?

Several factors can lead to the P0494 code being triggered, including:

• A malfunctioning secondary air injection pump or fan.
• Blockages or restrictions within the air intake or exhaust systems.
• Wiring issues such as shorts or breaks in the connections to the pump.
• A faulty ECM or a software issue causing incorrect readings from connected sensors.

How to fix P0494?

To resolve the P0494 fault code, the following steps can be taken:

• Begin by inspecting the secondary air injection pump and its related components for any signs of physical damage or wear.
• Check the wiring and connectors for any corrosion or disconnection that may impact the fan's operation.
• Clear any blockages in the air intake or exhaust system that could affect airflow.
• Replace the secondary air injection pump or fan if it is determined to be faulty through testing.
• If needed, reprogram or replace the ECM to ensure it communicates appropriately with the system.