SL/R230: P2003 (malfunction of secondary air injection (function chain) (p0410))
Thread Starter
Junior Member
Joined: Feb 2009
Posts: 68
Likes: 4
From: CT, USA
2005 E500, 2004 SL600
P2003 (malfunction of secondary air injection (function chain) (p0410))
I have a 2004 SL600 that has a Check engine light on. I read the codes and it is p2003 (malfunction of secondary air injection (function chain) (p0410)).
Attached is a video of what I believe is the air injector running.
Has anybody dealt with this error? What is my plan of attack to resolve this issue.
Thanks
Attached is a video of what I believe is the air injector running.
Has anybody dealt with this error? What is my plan of attack to resolve this issue.
Thanks
Senior Member
Joined: May 2020
Posts: 444
Likes: 55
From: North Carolina, USA
2004 SL500AMG, 2003 SL500 USA
I had a persistent yellow dash check engine light. I kept erasing a code about engine sensor or injector. I finally used MAF cleaner sprayed down the throat of the MAF. Then I snugged my gas cap down tighter. It had stopped screwing down with normal force. I screwed it down another 16th turn with more force. Finally, the yellow light went away.
Super Member
Joined: Sep 2021
Posts: 537
Likes: 115
From: Ann Arbor, MI
2004 SL600
I also has that same error a while back.
I found the easiest fix was to disable the secondary air pump in Xentry.
Later when I removed the engine to replace it wish the AMG version, I discovered that the vacuum line controlling the air pump had failed. This vacuum line is under the right side intercooler and has a sharp 180 degree bend in it. It split in the 180 degree bend. I replaced all vacuum lines on both M275 engines with silicone lines. That 180 degreed vacuum line connects to the air pump control valve; I suspect its either that vacuum line or the control valve.
BTW - you only have to lift the intercooler a bit to see an access the line; you can keep the cooling lines connected.
I found the easiest fix was to disable the secondary air pump in Xentry.
Later when I removed the engine to replace it wish the AMG version, I discovered that the vacuum line controlling the air pump had failed. This vacuum line is under the right side intercooler and has a sharp 180 degree bend in it. It split in the 180 degree bend. I replaced all vacuum lines on both M275 engines with silicone lines. That 180 degreed vacuum line connects to the air pump control valve; I suspect its either that vacuum line or the control valve.
BTW - you only have to lift the intercooler a bit to see an access the line; you can keep the cooling lines connected.
Newbie
Joined: Oct 2024
Posts: 10
Likes: 0
You cannot see the secondary air pump. I have a 2003 SL55 AMG. The secondary air pump is between the tire and bumper on the front right side of the car. If the pump is working, then you can hear it when you first start the car. I started my car and put my head near the front right headlights. I could hear a high pitch whine for about 40 seconds, and then it stopped. If you don't hear the pump, then the problem may be the relay that provides power to the pump. That was my problem, but I could not tell which relay it was from the documentation. The mechanic found the problem. The contacts on the relay were completely "worn" away. It could also be a bad pump.
Super Member
Joined: Sep 2021
Posts: 537
Likes: 115
From: Ann Arbor, MI
2004 SL600
Hard to me sure, but I doubt you would fail as there will be no codes related to the pump after it is coded out.
Fortunately I'm in Michigan where there still is no emission testing.
From AI search:
The secondary air pump on a Mercedes-Benz R230 (SL-Class) is an emission control component that forces fresh, oxygen-rich air into the exhaust manifold immediately after a cold start. This process rapidly heats up the catalytic converter, enabling it to reach operating temperature faster and significantly reducing harmful hydrocarbons and carbon monoxide emissions during the initial, rich-fuel combustion phase.
Since your emission test is with a warm engine, even less likely there would be a problem.
Still, did you look for a cracked vacuum line yet? On the M275 its a 3" long line with a sharp 180 degree bend in it.
Fortunately I'm in Michigan where there still is no emission testing.
From AI search:
The secondary air pump on a Mercedes-Benz R230 (SL-Class) is an emission control component that forces fresh, oxygen-rich air into the exhaust manifold immediately after a cold start. This process rapidly heats up the catalytic converter, enabling it to reach operating temperature faster and significantly reducing harmful hydrocarbons and carbon monoxide emissions during the initial, rich-fuel combustion phase.
Since your emission test is with a warm engine, even less likely there would be a problem.
Still, did you look for a cracked vacuum line yet? On the M275 its a 3" long line with a sharp 180 degree bend in it.
Last edited by mrvedit; May 12, 2026 at 12:35 PM.
