Here are the results for the codes I read on my 1993 400E:

PIN 7:
6. Starter lock-out/backup lamp switch.
11. Closed throttle recognition signal to engine control module (HFM-SFI or Left LH-SFI) Fuel safety shut-off to engine control module (HFM-SFI or left or right LH-SFI)

PIN 19:
4. Air injection system faulty hot film mass air flow sensor with hot wire.
17. Data exchange malfunction between individual control module.

PIN 30:
3. Driver Airbag squib

Now the question is what do these codes mean? I can tell that there is some problem with my Air Pump and possibly MAF...I would like to try to solve these problems so I can clear the codes and turn the Check Engine light off.

Thanks
-Landon

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• 1993 Mercedes-Benz 400E *146,000 Miles*
• 1985 Mercedes-Benz 300SD Turbo Diesel Biodiesel *SOLD @ 346,000 Miles*
• 1984 Mercedes-Benz 300D Turbo Diesel Biodiesel *SOLD @ 284,000 Miles*

You have to clear the codes first, and then see what comes up again. these might be codes from previous (already repaired) problems......

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1993 300E, 2.8 M104 .....

In order to clear them do you just hold the button down for 8-10 seconds?

__________________

• 1993 Mercedes-Benz 400E *146,000 Miles*
• 1985 Mercedes-Benz 300SD Turbo Diesel Biodiesel *SOLD @ 346,000 Miles*
• 1984 Mercedes-Benz 300D Turbo Diesel Biodiesel *SOLD @ 284,000 Miles*

yes i think. i have always had a hard time clearing mine though

there are a couple of good posts about this, if you search you will find them...this site is a goldmine of information.....

post your codes after they are cleared and after you've driven for a day or so...that will give you a better idea about what is going on,,,,

good luck!!

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1993 300E, 2.8 M104 .....

I cleared all of them and so far (without driving it) the only codes that are still present are:

PIN 19:
4. Air injection system faulty hot film mass air flow sensor with hot wire.
17. Data exchange malfunction between individual control module.

__________________

• 1993 Mercedes-Benz 400E *146,000 Miles*
• 1985 Mercedes-Benz 300SD Turbo Diesel Biodiesel *SOLD @ 346,000 Miles*
• 1984 Mercedes-Benz 300D Turbo Diesel Biodiesel *SOLD @ 284,000 Miles*

I think you should be able to clear them all. codes should not be there unless it is driven after clearing....

maybe give it another try?

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1993 300E, 2.8 M104 .....

I tried about 5 times they wouldn't go away...

__________________

• 1993 Mercedes-Benz 400E *146,000 Miles*
• 1985 Mercedes-Benz 300SD Turbo Diesel Biodiesel *SOLD @ 346,000 Miles*
• 1984 Mercedes-Benz 300D Turbo Diesel Biodiesel *SOLD @ 284,000 Miles*

I have no clue, some of the other members will help with this i am sure....

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1993 300E, 2.8 M104 .....

If you take off the black lid to the modules (where it says battery in trunk), there should be about 4 small Delco fuses on top of one of the modules (I think it's the base module). You may want to check those. It's a cheap and easy fix, if it will work.

You may want to pull those modules out and reinsert them while you are there, in case there is a contact issue.

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles

Well so far I have been driving for a day now with no check engine light...Hopefully it stays that way.

How exactly do you pull those modules out?

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• 1993 Mercedes-Benz 400E *146,000 Miles*
• 1985 Mercedes-Benz 300SD Turbo Diesel Biodiesel *SOLD @ 346,000 Miles*
• 1984 Mercedes-Benz 300D Turbo Diesel Biodiesel *SOLD @ 284,000 Miles*

If it's not broken, I wouldn't mess with it. The modules slide down into vertical slots and can be pulled out by hand (Mercedes makes a tool, though).

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles

Well I just ordered an LH Module out of a 1992 400E and it will be here tuesday so I'm going to have to take the old one out

__________________

• 1993 Mercedes-Benz 400E *146,000 Miles*
• 1985 Mercedes-Benz 300SD Turbo Diesel Biodiesel *SOLD @ 346,000 Miles*
• 1984 Mercedes-Benz 300D Turbo Diesel Biodiesel *SOLD @ 284,000 Miles*

Check the wires leading up to the HMF for cracks.

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600SEL '91
300E 4Matic '88
240D '83
280SE '77
350SE '73
The most complex systems can fail in the simplest way.
Contra verbosus noli contendere verbis, sermo datur cunctis, animi sapientia paucis.

i don't believe in the lord! He's never bought me a Mercedes Benz.

What is the HMF?

After clearing all my codes and driving for about a week I am coming up with the same code:

PIN 19:
4. Air injection system faulty hot film mass air flow sensor with hot wire.

I have searched this forum in and out to see if there is a fix for this problem. So far from the information I have gathered, other people who have had this code experience "surging" at idle. My car does this pretty consitently. I am pretty sure the problem is not the Air Pump as it sounds normal, the clutch engages and disengages, and the bearings seem fine. Could the problem be with my MAF Sensor or a bad connection to it? Thank you for all your help and information.

__________________

• 1993 Mercedes-Benz 400E *146,000 Miles*
• 1985 Mercedes-Benz 300SD Turbo Diesel Biodiesel *SOLD @ 346,000 Miles*
• 1984 Mercedes-Benz 300D Turbo Diesel Biodiesel *SOLD @ 284,000 Miles*

That code description doesn't sound right for a 119 motor. And you're checking pin 4 and getting no codes? Have you checked the vacuum lines around the air pump?