P0410 code-- Mercedes C230 1997 --162K miles

Chaud

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#1
Make
Mercedes
Model
C230
Year
1997
Miles
162K
Engine
4 cylinder 111.974, Chassis 202.023
Check engine light came on and code pulled was P0410 air injection system issue. I found air pump was working well, a small tube connected to air valve where air pump output connects has some vacuum when I put my finger on it. Once pump shuts down this tube has no vacuum as it should. It appears system is working but can’t seem to find where the problem is. One interesting thing to note is when I parked the car “check engine light” was on. But when I start the car again next day there is no check engine light during the whole drive. But when I start the engine when it is somewhat hot, after some driving this light comes back again. My question is, if check engine light comes on, shouldn’t it stay on until problem fixed. But I see it goes away after engine turned off and then comes back. I am thinking may be O2 sensor has worn out but car runs perfect, smooth and has lot of pickup. Appreciate your thoughts what it is and what should I check or replace. Thanks
 

grcauto

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#2
Do you want to test or replace? If test, what tools do you have?
 

Chaud

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#3
Thanks grcauto for your help. I have most of the tools for testing if not I can get them. Just to name few like obd2 analyser not bidirectional, vacuum gauge, voltage/current test meter and pretty much every tool.
 

Chaud

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#5
Here's the vacuum and wiring diagrams for your Benz.
Thank you so much for this information. I was able to understand view 1 but the other 3, I may have to go back to college again to learn about the wiring. I believe View 1 is good enough to troubleshoot. Here is some info from today. When I parked the car overnight it had check engine light on. But today when I started the car, check engine light was gone. I drove enough and engine temp. was in normal range. I did my shopping, started the car again and came home, but no check engine light lit. However, when I hooked the obd2 analyser, it still shows P0410 code. So where should I start checking to find the defective component, hose or wiring.
 

grcauto

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#6
I think you are retrieving the old code and not new. See if you can erase that code then drive it and see if the code returns.
 

Chaud

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#7
I am afraid to erase this code because it will also erase all the smog related tests which are stored in the ECU. I did once and it took me three months and 310 miles of driving to complete all of them. Smog test is due next month so want to be careful. If problem got fixed by itself which I doubt it will, then ECU will turn off this pending code anyway. So I have to wait and see what happens.
 

Chaud

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#9
I have two scan tools and both say all smog date stored in the computer memory will be erased if I erase P0410. In April, I did not believe so I said ok delete the code. To my surprise all 8 or 9 smog tests were erased and it took me 3 months to get them all checked and stored again. Catalyst test was the last one completed and right after completion "check engine light" comes on. It tells me it could be downstream O2 sensor which could be bad. I wish I could turn the air pump on and see if I see a big change in voltage because fresh air will have lot of O2 in it while exhaust should have none. I will check this tomorrow.
Well, the good news did not last long. Today I drove the car and while coming back "check engine" light came on. So it is not pending anymore.
 
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#10
Your scan tool can't erase it?
This is a tricky problem to solve . I checked O2 sensors health and they look good. Now decided to track backward. It means when I start the car and air pump comes on momentarily, does the air come out of the pipe which is connected to exhaust manifold or not. If yes, then everything is working as it should. However, if no, then either the air valve is bad or weak or no vacuum to open it. so that is my plan I thought I should mention so everyone knows what I am doing.
 

nickb2

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#13
So it is not pending anymore.
This is good, seeing you don't have bi directional, this will help pin point without to much pid data and bi directional testing.

Of note chaud, it is totally normal for a drive cycle to not complete for some reason, and that is usually when a readiness monitor does not complete, but also does fail a criteria in the mode six.

So I invite you to try to do a proper drive cycle whilst respecting all monitors. If one of those fails, check engine will always light up erratic, lest not forget, although it is a mercedes, t is after all a 97 and still ruled by bosch logic back then.
 

nickb2

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#14
Also, grc auto pinned that one also, if you don't erase originating code, this will MOST deffinatley prevent a drive cycle to complete, because from the get go, it is pre programmed to go into a algorythm limp in mode, but will self erase limp in mode at start up and self check, hence check light going out. But KAM (kam "keep alive memory" was predominant back then). so this is essentially your problem right now. SO just erase it, follow directions and we should in principal get to the basic of the bosch.