triangle12

I have an 05 C55 amg with 127k miles. Two months ago the secondary air pump was replaced. Last week engine light came on and autozone code reader said P0410 (secondary air pump). Took it to local dealer and there computer came up with a fault code p2003 not P0410. After spending $840 to replace an electrical module (they call front SAM), they then tell me the pump is bad too. They want $1500 to replace the pump. The pump is right on top and I wanted to know if I would mess up anything with the computer/module if I replaced it myself? Does it need to be OEM? I saw a new one on ebay for $150. Also, who ever replaced the air pump hardwired it rather than using a connector. Not sure why someone would cut off a electrical connector just to hardwire. Any help would be greatly appreciated.

gofisch

Is the pump that is bad the one you just had replaced? Does it still have a warranty?

insame1

You can do it yourself. There is even a repair guide out there somewhere. What does your voltage look like.

Rocman8

Does the pump run? At that mileage it could be just a cracked or soft vacuum supply line for the switchover valve. Was the relay replaced when the pump was replaced? The relay is usually the cause for the pump burning out.

triangle12

After replacing SAM, the dealer checked power going to the pump and it's good. So they say the pump is shot. I don't think the relay was replaced when they changed the pump. It's still the purple relay with Mercedes logo, I would assume an aftermarket relay wouldn't look like that. They used a Bosch pump, so it's not a cheap part.
Sounds like you guys think it could have been the relay that caused the pump to go out (since they didn't change it with the pump). Any thoughts on where I could get a connector, in case the hardwire was a possible cause. Would any of you use the ebay pump for $150 or go with another Bosch?

Rocman8

If they are telling you it needs another pump then why dont they parts warranty it? What happens is the old relay sticks and causes the pump to run continuously until it burns out. Why did they replace the Sam? The Sam Comes with all the new relays and fuses in it so not sure why they didn't just do the relay and fuse.

triangle12

This local dealer didn't replace the pump. I live in MO now, and the pump was replaced at a small shop in CO on 9/30. I guess that shop didn't replace the relay at that time. Since they just replaced SAM, my engine light isn't on now but I'm sure it will come back since the pump isn't working. So, I shouldn't have to buy a new relay since the SAM was replaced?

Rocman8

correct. Sam Comes with everything.

triangle12

Thanks!

LUV2SPD

I have 95k miles in my C55 and one day the secondary air pump didn't shut down. It heated up and sounded like it burnt up when it finally turned off. I thought I had to replace it, but it turns out it still works. After this incident I went home and unplugged the fuse and relay, looked through everything and it seems to be working ok now. Here is a video showing how to replace the pump. It only supposed to come on for around 30 seconds to pump fresh air into the exhaust when the engine is cold, it is for emission reasons. I'm hoping to reflash the ECU next summer, but I have to check if this eliminates the secondary air pump kicking in as well. If it does, I will be removing this stupid pump completely; it's an eyesore in the engine bay.

LUV2SPD

Here is a video that explains what the secondary air pump does and what the common problems are:

daynger

Hi Guys, mine appears to run all the time when the car is running, it shuts down with engine shut down though.
Is this the relay problem or does the relay problem run the pump after engine shutdown?
Any other ideas?
Thanks

Rocman8

Pull the purple relay and find out

daynger

That wont prove anything except that it is the purple relay that runs the pump.

Rocman8

if it's running for anything longer than a minute at anytime then pull the relay. If it shuts of then that's your problem.

LUV2SPD

When your car's engine is cold, open the hood after you start your engine and listen to the pump running, it should shut off about 30 seconds. The engine is loud, so if you can't tell if the pump is running you can put your hand on the body of the pump to feel if it's running and when it is shutting down. You can pull the purple fuse to see where the problem is. Just remember that after you started your car once, starting it again shortly will not re-start the air pump since your engine is already warmed up.

daynger

That still wont isolate the problem though will it?
The relay must be triggered by likely an ECU output which will be told to turn the pump on via some inputs, if i pull the relay the pump will stop, thats a given, but replacing the relay with a new unit will be pointless if the relay is still being driven on by the ECU constantly.
What tells the ECU to turn on the SAP relay?
Temp input?
Ill likely just get a relay anyway and replace to see if it goes away as they are cheap enough. but if its not the relay, where to from there?

Rocman8

you are right but I'm saying if it's running anytime more than 30-60 seconds then it's 99.9% the relay. The ECU commands the pump to turn on but I've never seen an ECU be the fault or any other components that would make the ECU turn the pump on. This is an extremely common issue an all Mercedes with secondary air as well as Mercedes airmatic pumps.

daynger

Ok cool, ill pull the relay and i can diagnose it with a multimeter aswell.
Thanks for the input.

daynger

Ok, relay and air pump are working OK, i thought they were the source of my constant whine when engine on.
Sounds like its supercharged, but isnt, where else should i be looking for engine whine?

Rocman8

Power steering? Guide pulley? I'd buy an automotive stethoscope and pin point it.