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Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53943
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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1999 ML320 Error Code p0410. Already replaced check value

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1999 ML320 Error Code p0410. Already replaced check value and air pump. code is still present.
HiCustomer you first need to determine if the air pump is coming on when the car is cold. A bad K40 relay can cause your problem. You next need to check your vacuum hoses to the system to insure they are all good. And make sure your shutoff valves are working and that your Y32 valve is working (not sure what you've already replaced). Finally you will need to monitor the reaction of the oxygen sensors when the system is activated with the scan tool. You may have restricted ports in the cylinder head or you may have a lazy oxygen sensor that doesn't react quickly enough to the additional air in the exhaust stream. I've attached a functional description of the system below.


Air Injection System Functional Description

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