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Pete
Pete, Mercedes Mechanic
Category: Mercedes
Satisfied Customers: 24659
Experience:  Over 15 years experience as a Mercedes dealer technician
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99 ml320: a p0410 code air pump seems to be working..runs fine

Customer Question

i have a 99 ml320 getting a p0410 code air pump seems to be working properly when cold the air pump turns on for about 1 min or so then shuts down put direct power to air pump and it runs fine
Submitted: 5 years ago.
Category: Mercedes
Expert:  Pete replied 5 years ago.
Hello,I will be glad to try and assist you with this,Welcome to Just Answer.

Hi.

This fault code will set when a fault is detected in the secondary air injection system on the vehicle,this may not be the pump at fault especially here since it comes on when the vehicle is started.

Most commonly I have found faulty oxygen sensors before the catalytic converter can fail and read incorrectly and cause this problem here.

There are shut off/check valves in line with this system as well that allow the air from the pump to enter the exhaust,if any of these fail this code can also set.

This system needs tested using a scan tool with function capabilities to command the air pump on so the valves operate as well when needed,jumping the pump wont open the valves up for proper operation.

Then once the pump is commanded on the data of the oxygen sensors before the catalytic converter needs observed on the scan tool.The voltages of these should drop below .1 volt or below 100 millivolts and hold for awhile while the pump is running.

If they drop below this but then come right back up then most likely one of the shut off/check valves has failed and needs replaced it depends on which sides voltage has rose back up.

If they do not drop or one of them doesn't drop then it may be a faulty shut off valve on that side of the engine or a faulty oxygen sensor.Most common is usually a faulty oxygen sensor.

If you don't have a scan tool to do this check then a shop or dealer would have to do this for you to determine what is at fault.Double check the hoses from the air pump are connected correctly to the check valves.

Let me know if you need anything else,click accept if you feel satisfied with your answer as this is how I get credited for my time,Thanks Pete!
Customer: replied 5 years ago.
ok this makes sense i also had an o2 sensor code p0135 bank1 sensor1 i earased the codes and the first one to pop back on was the air pump code so im assuming that this o2 sensor could be the problem and not the air pump what are your feelings on this...thank you matt
Expert:  Pete replied 5 years ago.
Definitely, I would lean towards this oxygen sensor at fault especially since it is common to cause the air pump code and you also have the fault code set at one point for the oxygen sensor.

This sounds like what is at fault that needs replaced and definitely where you should start to see if it corrects both of these faults,most likely it will.

Let me know if you need anything else,click accept if you feel satisfied with your answer as this is how I get credited for my time,Thanks Pete!