hi! could you tell me what is the part shown here:
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's buzzing for about a minute when cold engine starts - i think something is wrong with it, but i don't know what it is..
- posted
13 years ago
E46 318i : what is that part and dos it have to be noisy?
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- posted
13 years ago
Secondary air pump. Helps emissions when the engine's cold.
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- posted
13 years ago
That is called the Secondary Air Pump. It will turn the Check Engine Light ON, eventually.
When the exhaust is cold, there isn't sufficient air to allow the CAT (catalytic converter) to do its job, so the secondary air pump is used to inject additiional clean air so the exhaust will come out clean. After the CAT heats up, the secondary air pump can be turned OFF because it is no longer needed.
The secondary air pump will cause the car to fail smog testing, but the engine won't care that you have it or not. There is no danger to the long life of the car without the secondary air pump, but you will make more dirty air for the few minutes that it is used, and you will fail any smog test that is required before you have it fixed. Well, yoiu will fail the smog test if the Check Engine Light is ON at the time of testing. The pump's noise is not always an indicator of failure.