DTC P0491 BMW
Secondary Air Injection System Insufficient Flow (Bank 1)
Secondary Air Injection System Insufficient Flow (Bank 1)
Description
Engine started, battery voltage must be at least 11.5v, all electrical components must be off, parking brake must be engaged (to keep daytime driving lights off), automatic transmission selector must be in park and the ground between the engine and the ch
Cause and Solution
Air pump output is blocked or restricted
AIR bypass solenoid is leaking or it is restricted
AIR bypass solenoid is stuck open or stuck closed
Check valve (one or more) is damaged or leaking
Electric air injection pump hose(s) leaking
Video Guide
Diagnostic Info
- DTC Code: P0491
- Brand: BMW