P0418 – Secondary Air Injection System Relay ‘A’ Circuit Malfunction

 

P0418: DIY Repairing Video Tutorial

https://youtu.be/cesxIRYA6jE

Check out nonda Auto DIY Center for more engine error code repairing videos.
https://www.youtube.com/playlist?list=PL-Lyko0O0oxHe1AGvzwAz-wokJPXAtW97

 

P0418 Possible Symptoms

  Engine Light ON (or Service Engine Soon Warning Light),Engine hesitation  

P0418 Possible Causes

  Faulty Air Pump inoperative,Air bypass solenoid harness is open or shorted,Air bypass solenoid circuit poor electrical connection  

P0418 Description

  An air pump is used on the vehicle to lower tail pipe emissions on start-up. The Powertrain Control Module (PCM) grounds the Air pump relay control circuit which energizes the Air pump. The PCM also grounds the Air combination valve vacuum control solenoid circuit, which energizes the Air vacuum control solenoid. Vacuum is then applied to both Air combination valve diaphragms which opens the shut off valves. The PCM enables both circuits simultaneously when Air system operations id desired. When the AIR system is active, then Air pump forces fresh air into the exhaust stream in order to accelerate catalyst operation. The AIR combination valves replace the conventional check valves. When the AIR system is inactive the shut off valves prevent air flow in either direction.