P0418Mazda Cx-30Years: 1996 - 2026
Secondary Air Injection System A Relay Circuit Malfunction
Reviewed by ASE Certified Technician
What does this mean?
Code P0418 indicates a problem with the secondary air injection system. This system pumps fresh air into the exhaust stream during cold starts to help the catalytic converter reach operating temperature faster.
Disclaimer: This diagnostic code is part of the standard OBD2 system and can apply to Mazda Cx-30 models manufactured from 1996 to 2026. However, please note that the presence of this specific code depends on your vehicle's exact engine configuration, options, and production year.
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Common Causes
Faulty secondary air injection pump
Stuck secondary air injection check valve
Damaged, chafed, or broken wiring harness
Corroded or loose electrical connector
Symptoms to Watch For
- Check Engine Light is illuminated
- Failed emissions test
- Rough or unstable idle
- Rotten egg smell (sulfur) from exhaust