Secondary Air Injection Pump replacement - FAQ?

Subscribe
May 9, 2015 | 06:58 AM
  #26  
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.
Reply 0
May 9, 2015 | 02:42 PM
  #27  
Quote: 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.
yes, but my pump is just noisy - doesn't run all the time...

is the relay located by the pump?
Reply 0
May 9, 2015 | 06:00 PM
  #28  
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.
Reply 0
May 9, 2015 | 10:41 PM
  #29  
Quote: 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.
awesome thanks!
Reply 0
May 11, 2015 | 05:07 AM
  #30  
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.
Reply 0
May 11, 2015 | 07:38 AM
  #31  
indeed..
yes indeed. that's what it is and how it sounds!
Reply 0
May 14, 2015 | 05:25 PM
  #32  
what's the part # for this relay?

i think i found it:

Quote: 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 Also note: the relay A0025421319 part has been replaced by a newer/updated part # by MB.
http://www.autohausaz.com/search/pro...YTqBoCzTbw_wcB

Reply 0
May 14, 2015 | 05:48 PM
  #33  
part number
lastest part number thru various updates is this: 0025427219. this is the relay part number.
Reply 0

MB World Stories

The Best of Mercedes & AMG

Explore
story-0

6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)

 Verdad Gallardo
story-1

Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun

 Verdad Gallardo
story-2

Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren

 Verdad Gallardo
story-3

8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine

 Verdad Gallardo
story-4

Flawlessly Restored Mercedes 190E Evo II Heads to Auction

 Verdad Gallardo
story-5

Electric Mercedes C-Class Unveiled: 11 Things You Need to Know

 Verdad Gallardo
story-6

Mercedes EQS Gets A Major Update: Everything You Need to Know

 Verdad Gallardo
story-7

5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve

 Verdad Gallardo
story-8

Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping

 Verdad Gallardo
story-9

10 Most Reliable Mercedes-Benz Models You Can Buy Used

 Verdad Gallardo
May 14, 2015 | 06:57 PM
  #34  
Quote: lastest part number thru various updates is this: 0025427219. this is the relay part number.
dang local stores like Autozone carry them for ~$56! :o

may just try the dealer!!! LOL
Reply 0
May 14, 2015 | 07:28 PM
  #35  
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 !
Reply 0
May 14, 2015 | 07:39 PM
  #36  
Ebay or AutoHausaz
Reply 0
May 16, 2015 | 06:55 PM
  #37  
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

Quote: dang local stores like Autozone carry them for ~$56! :o

may just try the dealer!!! LOL
Reply 0
May 16, 2015 | 10:26 PM
  #38  
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
Reply 0
Jun 27, 2019 | 01:24 PM
  #39  
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?
Reply 0
Jun 28, 2019 | 07:03 PM
  #40  
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.
Reply 0
Subscribe
Currently Active Users (1)
 
story-0

6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)

Slideshow: Not every Mercedes design becomes timeless, some feel stuck in the era they came from.

By Verdad Gallardo | 2026-05-12 18:09:07


VIEW MORE
story-1

Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun

Slideshow: Yes, Mercedes built manual cars, and some of them are far more interesting than you'd expect.

By Verdad Gallardo | 2026-05-02 12:36:58


VIEW MORE
story-2

Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren

Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.

By Verdad Gallardo | 2026-04-29 11:19:28


VIEW MORE
story-3

8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine

Slideshow: Before curves took over, Mercedes mastered the art of the straight line, and some of those shapes still look right today.

By Verdad Gallardo | 2026-04-25 12:05:49


VIEW MORE
story-4

Flawlessly Restored Mercedes 190E Evo II Heads to Auction

Slideshow: The 190E Evolution II shows how a homologation necessity became a six-figure collector icon.

By Verdad Gallardo | 2026-04-22 17:53:47


VIEW MORE
story-5

Electric Mercedes C-Class Unveiled: 11 Things You Need to Know

Slideshow: Mercedes is turning one of its core nameplates electric, and the details show just how serious this shift is.

By Verdad Gallardo | 2026-04-21 13:58:06


VIEW MORE
story-6

Mercedes EQS Gets A Major Update: Everything You Need to Know

Slideshow: Faster charging, longer range, and a controversial steer-by-wire system define the latest evolution of Mercedes-Benz EQS.

By Verdad Gallardo | 2026-04-15 10:35:34


VIEW MORE
story-7

5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve

Slideshow: These overlooked Mercedes-Benz models never got the spotlight, but they quietly delivered more than most remember.

By Verdad Gallardo | 2026-04-13 19:35:45


VIEW MORE
story-8

Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping

Slideshow: A well-used 1991 Mercedes-Benz 300D with more than one million miles is now looking for a new owner, and it still appears ready for more.

By Verdad Gallardo | 2026-04-10 10:05:15


VIEW MORE
story-9

10 Most Reliable Mercedes-Benz Models You Can Buy Used

Slideshow: From bulletproof sedans to surprisingly tough SUVs, these Mercedes models proved that the three-pointed star can go the distance.

By Verdad Gallardo | 2026-04-08 09:55:49


VIEW MORE