The P0410 engine fault code is common among late ’90s and early 2000s Mercedes vehicles. The code can come from a number of different problems which makes it slightly more challenging to properly diagnose and fix. Fortunately, Mercedes P0410 problems don’t usually lead to any serious engine problems or failures. You can typically drive around for awhile with this engine code. However, finding and fixing the issue help prevent any minor issues you can have from this code like rough idling, lack of acceleration, and so on.

This guide is going to discuss what the P0410 engine code means on Mercedes vehicles, what causes the error code, and how you fix it.

Mercedes P0410 Code Meaning

When scanned with an OBD reader, P0410 will read:

“Secondary Air Injection System Malfunction“

The code isn’t very descriptive and has to do with a technical engine component: the air injection pump. The air injection pump is also frequently referred to as a smog pump and is an emissions-related system that pumps oxygen into the exhaust system to help further burn exhaust gases to make them cleaner.

While this engine code has to do with the air pump, it doesn’t necessarily mean that the air pump itself is bad. The engine’s computer uses the exhaust’s O2 (oxygen) sensors to read the amount of oxygen in the exhaust. When the air pump is properly functioning it should read higher oxygen levels in the exhaust. When the oxygen levels are lower than they should be, the P0410 warning light will come on.

Mercedes aren’t the only engines to suffer from P0410 problems. A lot of other vehicles and manufacturers use secondary air pumps so this can affect other vehicles, but it does tend to be a pretty common problem on some of the older Mercedes engines.

What Can Cause Mercedes P0410 Issues?

There are a number of components that can cause a P0410 code to come up on your Mercedes. The most obvious is the air pump failing, but there are other parts that can cause this too so the issue isn’t always with the air pump itself.

First off, the air pump usually has a fuse and relay that control electrical power to the pump for it to operate. When these fuses and relays fail the pump will stop working. This is only true for electric air pumps, some Mercedes have belt-driven pumps and therefore don’t use electricity to operate.

Secondly, the oxygen levels are measured by the O2 sensors. Therefore, a bad or failing oxygen sensor can lead to incorrect readings and cause this also. Additionally, vacuum leaks can throw off readings as well so it could be a small vacuum hose that came loose.

Lastly, the issue can be with the air pump itself or with the check valves on the air pump. The check valves sit between the pump and the exhaust system and basically prevent issues with water or too much air pressure getting into the air pump and causing it to fail.

To summarize, a Mercedes P0410 engine code can be caused by:

• Bad fuses or relays
• Faulty oxygen sensors
• Vacuum leaks or vacuum actuators
• Bad air pump
• Failed air pump check valve

Now, there are a few other less common things that can cause this such as a dirty EGR system and blockages in the cylinder head passages which tend to be most common on the M112 engine.

Diagnosing a Mercedes P0410 Code

The number of things that can lead to this engine code can make it somewhat difficult to diagnose and actually fix. The best way to diagnose problems is via the process of elimination, and starting with the easiest things to check.

Fuses & Relays

Fuses and relays are the easiest first thing to check. They work by controlling electricity flow from the battery to the air pump, so when they fail the pump won’t have the electrical power it needs to function properly.

You can find diagrams for the fuses in your owner’s manual – just about anyone should be able to check the fuses, even if you don’t have any DIY knowledge.

Vacuum Hoses & Actuators

Engines need vacuum to properly function—vacuum is what helps the engine suck air through the intake system. There are a number of small vacuum hoses within Mercedes engines that can become loose or become brittle and leak.

Check your engine bay for any loose hoses. If all the hoses look good then it could be an issue with the vacuum actuators. The actuators are usually pretty easy to access and can go bad which would create a loss of vacuum and therefore cause this code.

Faulty O2 Oxygen Sensors

O2 sensors read how much oxygen and unburnt fuel is in the exhaust system. The whole purpose of the secondary air pump is to eliminate the amount of unburnt fuel and harmful gases in the exhaust. If the O2 sensors aren’t working properly it makes the engine’s computer think that there is an issue with the air pump, therefore causing a P0410.

Air Pump & Check Valve Issues

On Mercedes the air pumps and check valves themselves really don’t fail very frequently. When a Mercedes P0410 code comes up it is caused a lot of times by small vacuum leaks or issues with the O2 sensors. But with that being said, the pumps and check valves themselves can fail which would lead to this issue as well.

It’s easier to check all of the other potential problems first before assuming the pump or valves themselves are bad.

Other Mercedes Issues

Lastly, as we briefly mentioned there are a few more unique problems that can cause this. The first is a dirty EGR system – the system that passes dirty exhaust gas back into the intake system to reburn it during the combustion process. The second is clogged passages in the cylinder head. These are both less common causes of the P0410 but if you have diagnosed all the other components without finding any problems then these are what you should look into next.

Symptoms of a P0410 Engine Code

• Rough idling
• Loud air injection pump
• Sluggish acceleration
• Engine codes for running lean and rich

A P0410 code won’t prevent you from driving your Mercedes. However, there might be some small but noticeable performance-related issues when the code is present. The severity of the symptoms usually depends on what part fails. Reading any other engine codes might help you pinpoint the exact problem so starting there is your best bet, then working through the causes mentioned above.

Mercedes P0410 Summary

The P0410 code is related to the engine’s secondary air injection pump system, which is also commonly referred to as an air pump or smog pump. The pump pushes oxygen into the exhaust system to help burn any leftover fuel in the exhaust system, therefore resulting in cleaner emissions.

The code, however, can be caused by a number of issues that aren’t directly the pump itself. It can be caused by bad fuses and relays, vacuum leaks or bad vacuum actuators, oxygen sensors, or the pumps check valves. Furthermore, Mercedes specifically has a few issues with clogged passages in the engine’s head and dirty EGR systems that can also trigger the P0410 fault code.

The best place to start diagnosing is to check the easy items like the fuses and then to look for issues with loose vacuum hoses in the engine bay. Driving with the engine light on with a P0410 is okay – it generally isn’t harmful to the engine but it will lead to some small performance-related issues. As always, fixing problems as quickly as you can once they arrive is the best way to maximize reliability and your engine’s lifespan.