Secondary Air Injection Monitoring: Notes
In order to reduce HC and CO emissions while the engine is warming up, BMW implemented the use of a Secondary Air Injection System in. Immediately following a cold engine start (-10-40°C) fresh air/oxygen is injected directly into the exhaust manifold. By injecting oxygen into the exhaust manifold:
- The warm up time of the catalyst is reduced
- Oxidation of the hydrocarbons is accelerated
The activation period of the air pump can vary depending on engine type and operating conditions.
Conditions for Secondary Air Pump Activation:
| REQUIREMENTS | STATUS/CONDITION IMS 43.0 | STATUS/CONDITION M73 |
|---|---|---|
| Oxygen sensor | Open Loop | Open Loop |
| Oxygen sensor heating | Active | Active |
| Engine coolant temperature | -10 to 40°C* | -10 to 40°C* Stage |
| Engine bad | Predefined Range | Predefined Range |
| Engine speed | Predefined Range | Predefined Range |
| Fault Codes | No Secondary Air Faults "currently present" | No Secondary Air Faults "currently present" |
The Secondary Air Injection System is monitored via the use of the pre-catalyst oxygen sensor(s). Once the air pump is active and is air injected into the system the signal at the oxygen sensor will reflect a lean condition. If the oxygen sensor signal does not change within a predefined time a fault will be set and identify the faulty bank(s). If after completing the next cold start and a fault is again present the "Service Engine Soon" light will be illuminated.