Guys,

Have and issue with my '97 w210.

Code is P0410 and I have replaced switch over valve, check valve, both bank 1 and 2 oxy sensors. Check for vacuum leaks, none. Secondary air pump is working. Cannot get rid of check engine light. Took to an indie and he check voltage between sensors and they check off as good. Indie says ports in heads are working and clear.

What the h#@#? Really need assistance on this one!

Sea foam job?

__________________
Norm K.
'97 E420 Sport
'06 E350 Sedan
'67 Mustang Coupe
'70 F-250
'15 VW Jetta

I've chased this on a on a M104 inline 6, I'd expect the operation to be same as a V8 but the hose routing would be different. If all else fails, a work around could be to insert a resistor in line with the O2 signal , a relay that jumpers out the resistor. This relay would be tied to the air pump wire so when the air pump runs, the O2 signal drops.

410 is secondary air injection problem. First how the system is supposed to work:

With a cold / luke warm engine start, the electric air pump operates, switch over valve opens ( vacuum control valve at front of engine ) to allow vacuum to be present at the check valve ( right side by the exhaust manifolds ).

This system introduces air into the exhaust ports to allow burning of fuel past the exhaust valve. It also provides a bit of extra oxygen for the cat converters.

After a few minutes, the air pump stops and vac valve closes. Once the engine is warm, you have made your first stop and the engine is at idle for 5 or so seconds, the air pump system turns on and the ECM looks for the front O2 sensor to drop in voltage due to excess O2. This test lasts about 4 sec and is done every trip as part of the OBD2 cycle. If the O2 voltage does not drop, a code will be set.

Now for the likely fix. There is a white nylon tube that runs under the ignition coil cover. It can become pinched when the cover is installed or it just gets brittle and cracks. A pinch / break here won't allow the check valve to open and allow air to flow.

The air injection ports on the manifold can get blocked with sooty stuff...

Replaced the white nylon tubes from the switch over valve and still got the stupid check engine light on.....

__________________
Norm K.
'97 E420 Sport
'06 E350 Sedan
'67 Mustang Coupe
'70 F-250
'15 VW Jetta

Bump....

__________________
Norm K.
'97 E420 Sport
'06 E350 Sedan
'67 Mustang Coupe
'70 F-250
'15 VW Jetta

How did your indie verify that the ports in the cylinder head are clear? If the pump and switchover gear are working correctly there aren't too many other possibilities....

I've fought this problem before and in my case the air injection ports in the cylinder head were plugged, many sources said that cylinder head removal with a hot-tank soak was the only way to clear the ports. I was able to clear the ports with a combination of solvents, reaming with EGR snakes, compressed air and time. There are ports to all 3 cylinders on each bank but I've found that the system will work well enough to evade the P0410 if you can just get one port clear.

The Star SDS and some other high-end scanner tools have a test procedure that will activate the switchover gear and energize the air-pump while also displaying the O2 sensor voltages. This takes a lot of the guesswork out of diagnosis and troubleshooting.

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98 Dodge-Cummins pickup (137K)
13 GLK250 (157k)
06 E320CDI (341K)
16 C300 (89K)
82 300GD Gelaendewagen (54K)

You need to view computer data and watch the O2 sensor readings when the air pump turns on. The voltage must drop when the air pump turns on.

My post 2 outlines how the system works and when you need to look at the data. ( when the OBD system runs the air pump test is when you need to view O2 voltages. )