Rtcmd

My 2011 ml350 check engine light came on when started yesterday morning. The error code gives P0410 Secondary Air Injection System. What does it mean and how should I diagnose the code to pinpoint the problem? Anybody out there who had same problem before please help. Thanks.

flybd5

You'll need to scan the car with a scanner that understands Mercedes codes. In some cases this means an air injection pump has failed and the fuse has blown because the motor is drawing too many amps, which requires the pump and the fuse to be replaced, but you won't know for sure what is wrong without the Mercedes code.

Maj. Dundee

With this code you can continue to drive the truck with no performance problems or worries, unless you are due for annual inspection shortly.

The following must be done with a cold eng. and the key out of the ign.

Access the engine compartment fuse/relay box and remove fuse 107 and see if it is blown. If not, reinsert and remove relay "E". There are no relays in this fuse box that can be substituted for trial purposes as they are needed to start the truck.

Go to the load compartment fuse/relay box and locate relay "M", rear defroster. It must be a gray relay and check it against the legend chart on the rear of the cover to make sure. If so, remove it and insert it in place of relay "E".

Turn key to pos.#2, and erase code P0410. Turn key off, wait 10 secs. and start eng. and see if the code returns.

Post back with results or if there are any questions.

Rtcmd

The scanner error codes defined P0410 Secondary Air Injection System had a fault for a predetermined period of time. The most likely solution is to replace Air Injection Pump and Relay.

Maj. Dundee,
Does the error code gets erased automatically or it is done manually? When switching M relay for E relay and try to start the truck to check if the code goes away, the original location of the M relay is empty. Am I right with this? If the code goes away, does it mean the relay is the problem? What if the code stays on, does it mean the air pump is bad? Appreciate your input. Thanks.

Maj. Dundee

Please just follow the instructions and don't worry about relay M.

Maj. Dundee

Any results?

Rtcmd

Maj. Dundee,
I haven't done it yet because of the cold weather here in the East Coast. I'll do it once the weather warms up a bit and I'll let you know.
By the way, I was thinking of just buying a new relay and replace the old one. I just thought it might be the issue since I don't hear the air pump runs when I start the truck. Shouldn't you hear it running for awhile after starting the truck?

shawndh

Rtcmd

I haven't done anything yet to correct the problem, but the check engine light came off after filling up gas on my truck. I have been driving it for several days now and the light has remained off. I'm not sure how it happened, but glad no more check engine light on the instrument panel. My concern now is if the P0410 code was erased or would still show when scanned again? Any chances that it was a wrong code that's why it cleared up without repair? Please advise.. Thanks.

Maj. Dundee

Code P0410 would have nothing to do with filling up the gas tank. If the CEL went off by itself, then the problem corrected itself.

If you scan the truck the code might not appear at all or the code might be listed as STORED which means that it was previously a valid/current code at one time. Simply erase the code.

Rtcmd

Maj. Dundee, is the code can only be erased by using a scanner? I don't have one and only went to an auto parts store to have it scanned. I want to buy one, but I know there are lots of them in the market. Which one is good for me to buy?

Maj. Dundee

If the CEL is not on and the code is stored, it will erase itself after a predetermined number of eng. starts.

This scanner will read and erase codes in all of the 43+ modules in your veh.

Rtcmd

Thanks Maj. Dundee.

andyclev

Just a quick note on my P0410 experience, 2006 ML350.

Turned out to be my pump, got an OEM for $123 and put it in myself, went ahead and changed the blue vacuum check valve ($9), and got a new relay ($12). Fuse was perfect, so did not replace that.

Repair took all of 20 minutes and all was fine for a few days when the P0410 code came back.

When had time I unbolted the bracket (did it in that sequence: unbolted bracket > air pump) and noticed that the two clear/yellowish vacuum lines were somewhat "pinched" behind the bracket, not broken but could see a little bit if pinch/stress on the line. Used a screwdriver to push them back, away from the bracket when I put it back on, and it's clear that there is not much room for those two vacuum lines, but they cleared (marginally) and no more return of the P0410 code!

These codes are best tackled by first figuring out if the air pump is coming on or not. Best to get a cheap stethoscope on first start of the day and put right on that thing, listening for a hair dryer sound. If it is NOT working then replace fuse and relay (passenger side fuse box, engine compartment). If that still does not fire up the pump then the pump is likely bad.

If fuse/relay/pump are working then likely culprit is the blue check-valve in the vacuum line that got mucked up.

That was my trial and error method and hopefully this will help someone else down the line.