P0418 Fault Code

Secondary Air Injection System Relay A circuit Malfunction

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

The P0418 code indicates a malfunction in the Secondary Air Injection System Relay A circuit. This system is designed to reduce emissions by injecting ambient air into the exhaust system during cold starts, which helps the catalytic converter reach optimal operating temperature more quickly. When this relay circuit experiences issues, it can disrupt the air injection process, leading to increased emissions and potential performance problems.

What are the symptoms of the P0418 code?

Drivers may experience a range of symptoms when the P0418 code is present, such as:

• Illuminated Check Engine Light (CEL).
• Decreased engine performance, particularly during cold starts.
• Increased exhaust emissions.
• Unusual engine noises, especially during warm-up periods.

What causes the P0418 code?

Several factors can trigger the P0418 code, including:

• A faulty Secondary Air Injection Relay.
• Damaged or corroded wiring and connectors in the relay circuit.
• A malfunctioning air pump.
• Issues with the engine control module (ECM) that fails to activate the relay correctly.

How to fix P0418?

To resolve the P0418 code, consider the following steps:

• Inspect the Secondary Air Injection Relay for signs of failure. Replace if necessary.
• Check all wiring and connections for damage; repair or replace any corroded or broken wires.
• Test the operation of the Secondary Air Pump and replace if it is defective.
• If the relay and pump are functioning correctly and the code persists, a diagnostic scan of the ECM may be needed to rule out internal faults.