Yesterday I replaced bad MAF on W124 E 220(M111.960) to fix rough idle, now I see HFM code 77, this particular model has O2 sensor and does not have CO potentiometer.

What could be the issue? is it the side effect of bad MAF? I tried clearing the code several times, but it keeps coming back.

P.S: Rough Idle and DTC 10 is fixed after MAF replacement.

Thank You

That code from HFM module?
Year?

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A Dalton

Yes it is from Pin 8, year is 1995.

What are you using to retrieve those codes ?

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A Dalton

I am using carsoft 7.4 from ebay.

I have that code as Not Used from HFM, but for US version HFM.
77 would be an HHT subcode for Flash code 31.
I assume you got the code MAF 10 from the DM module?
Does this chassis have the Built-In Led/SW combo at the 16 socket diagnostic box?

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A Dalton

I only have US version codes , but you may want to build this simple tool and see what you get at pins 3, 8, and 14.

E320 16 PIN DTC Charts inc. pin 8, pin 14

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A Dalton

Will try that out on Pin 8 coming weekend, this model only has socket for pin 1, 6, 7, 8, 10 and 16.

I am not familiar with the Euro set-up.

The pin 1 and 16 would be ground [1] and 12v+ [16] to power the led, but I have no info on the others or codes for that model.
I would expect HFM to still be 8.........

Which pin did you get the code 10 from?

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A Dalton

Yes pin 8 is HFM and I got code 10 from pin 8.

From what I could find out
Pin 6 - AirBag
Pin 7 - A/C
Pin 10 - Not used for my model

I see a TN signal for 10...but , US version.

i would still go into 8/HFM with a led tool and see what comes back as Flash code. Your scanner may be showing the Benz HHT tester format for the 77 b/c there is NO flash code 77, [ only up to 50]... but that could be b/c flash format for 77 is 31 blinks...which list as "Not Used" , but maybe it is used on Euro HFM ???????????????????????

{ Benz HHT numbers are digital and not the same as analog Flash format]

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A Dalton

bump!

Is there anyway we can do "Vehicle Version Recognition" without HHT. Anyone?

Thank You

The problem was ECU/ECM was coded as without KAT, whereas my car has KAT. Coded it back as with code for KAT version and error vanished.