Secondary Air Injection Pump replacement - FAQ?
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From: PALM BEACH GARDENS, FLORIDA
2004 MERC E55
relay...
yes get it replaced! its the relay that caused the pump to run continuously in the first place. so the relay is what gives the pump power to run. definitely change the relay.
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From: Folsom, CA
2005 E55 AMG
is the relay located by the pump?
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Joined: Jun 2009
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From: PALM BEACH GARDENS, FLORIDA
2004 MERC E55
relay location...
the #40 relay is inside the fuse box on the drivers side under the hood. its the big black square relays, once you remove that cover over the fuses, you will see all the big relays right there and its #40 that you will replace.
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From: Folsom, CA
2005 E55 AMG
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From: Chicago
03 E55 AMG, 06 Harley Road King Custom 06 Ram 2500 Cummins, 97 Firebird Race Car, 88 Cutlass Supreme
Is the SAI pump the noise that sounds like a small jet airplane about to take off from under my car after idling for a few minutes after a cold start? Winds up and runs a few seconds than shuts off again.
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From: Folsom, CA
2005 E55 AMG
what's the part # for this relay? 
i think i found it:
http://www.autohausaz.com/search/pro...YTqBoCzTbw_wcB
i think i found it:
What were you able to find out?
From what i understand, in my 04 LHD (US)- the 40 fuse and the" R" relay next to it in the box under the hood needed replacing after the blown pump is swapped out.
Do you know if there is still additional fuses under the gas pedal on the US version that need to be swapped? Also note: the relay A0025421319 part has been replaced by a newer/updated part # by MB.
From what i understand, in my 04 LHD (US)- the 40 fuse and the" R" relay next to it in the box under the hood needed replacing after the blown pump is swapped out.
Do you know if there is still additional fuses under the gas pedal on the US version that need to be swapped? Also note: the relay A0025421319 part has been replaced by a newer/updated part # by MB.
Last edited by Toadster; May 14, 2015 at 05:49 PM.
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MBWorld Fanatic!
Joined: Dec 2011
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From: Folsom, CA
2005 E55 AMG
Senior Member
Joined: Jun 2009
Posts: 482
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From: PALM BEACH GARDENS, FLORIDA
2004 MERC E55
i got some extra i'm sure..
I only paid $25 and I am sure I should have extras. let me know if the dealer is way more, I can ship you this one. just $25 man. I will cover shipping. find out and hope you can find it cheaper !
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05 E55 AMG, E320 CDI, Turbo E46 M3,IS300 2JZGTE,VQ35 Turbo Maxima, Mercedes 300D
These are standard 40A mini relays. If you don't mind getting them without the retaining hooks, use these:
http://www.ebay.com/itm/New-Hella-Relay-Mercedes-E-Class-SLK-CLK-SL-S-CL-C-G-CLS-R-Sedan-R350-2008-/351196037802?hash=item51c4ea42aa&vxp=mtr
or these:
http://www.ebay.com/itm/OEM-Hella-Relay-Mercedes-Fuel-Pump-Fan-Air-Suspension-4RA-007-791-011-NEW-/151591745919?hash=item234b92797f&vxp=mtr
http://www.ebay.com/itm/New-Hella-Relay-Mercedes-E-Class-SLK-CLK-SL-S-CL-C-G-CLS-R-Sedan-R350-2008-/351196037802?hash=item51c4ea42aa&vxp=mtr
or these:
http://www.ebay.com/itm/OEM-Hella-Relay-Mercedes-Fuel-Pump-Fan-Air-Suspension-4RA-007-791-011-NEW-/151591745919?hash=item234b92797f&vxp=mtr
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From: Folsom, CA
2005 E55 AMG
got the pump replaced today 
got a Hella relay $9
nice and quiet now - no more jet engine on startup! WOOHOOO!!
BTW - that ebay guy is GREAT! I highly recommend him
got a Hella relay $9
nice and quiet now - no more jet engine on startup! WOOHOOO!!
BTW - that ebay guy is GREAT! I highly recommend him
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03 SL55 AMG
Replaced my secondary air pump a week ago w/ an aftermarket part. I know the pump kicks in for the first half a minute or so right after starting the car but the difference now is the noise. I can clearly hear the pump running compared to when the original part was on. I've been driving my SL55 for over a year now and just recently got the CEL so I assume the pump was fine till a month ago but never noticed the sound of the pump running before. Do you think this is normal or is it the part being a cheap aftermarket?
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Joined: Oct 2010
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2004 E55 AMG
It's funny, by the time my OEM pump failed, it was noisy as a buzz saw for 30 seconds or so. I sent it to someone recommended from this forum to rebuild it and it has been much quieter, going on five years now. I occasionally hear it turn on while sitting at a stop light, but it's still nowhere near as loud as it was originally. All that said is to say, yes, it is probably normal. Good luck.
