1994 E320 fault code 35 and 84
 

I have a 1994 E320 wagon with check engine light on. Shop reports MB fault codes 35 and 84 and suggests new air flow sensor and/or O2 sensor. Repair would be in excess of $700 but shop could not guarantee that check engine light would go out. Can anyone provide me some info that would raise my confidence that a new air flow sensor and/or O2 sensor is a good plan? Car runs very well, but intermittantly surges (up to 1200 rpm) when at stop light with transmission in drive. Seems to happen more in cold weather. Placing transmission in park reduces fluctuations. Car has 175,000 miles.

Also, is it possible to make modify or buy a code reader for this make and model so I can read my own fault codes?

Thanks.

J. M. van Swaay

Both codes listed are for a bad air mass sensor! MB part number 000-094-05-48 OR 000-094-05-48-88(rebuilt)! $400. list for the new one OR $310. for the reman unit. Takes less that 5 minutes to replace!


AS far as reading codes on that car you can do that on the DIAGNOSTIC module by pressing the button on the diagnostic connector under the hood.

TRY using the search function HERE. Blink codes

Do a search under led s/w. You can make a code reader for around $10.

As M.B. Doc mentioned, you can get the emissions related code from the DM near the battery, but to get codes from the various modules like the ECM etc., you will have to buid a reader.

Interesting . . . .
 

I don't show DM codes going higher than 50! Also don't show code 35 for a 124.032/052 car?????

You should be able to read the codes yourself: you should have a push-button/LED sw combo near the battery. Check my page, Menu#2 for what it looks like: called "X11/21sw" in the diagram.

With that sw/LED you can read codes from the Diagnostic Module. To read codes from the other ECUs in the car, you will need to build or buy as scanner.

The scanner shown on my page, MENU#3 shows a Mercedes compatible scanner that does all that you want. However, it's not cheap.

On the bottom of Menu#2 page, you see plans for a DIY code reader that can be built from Radio Shack parts. It will allow you to read codes from the other ECUs in the car. And, of course, it's cheap. But you need soldering and some construction skills.

I recently bought a brand new OEM air mass sensor from The Benz Bin. It cost about $300, shipping included.

JimF, there are two sets of codes: one for the Impusle Counter Scan Tool and the other for the Handheld Tester (HHT).

For example HFM code 13 refers to O2 system at limit (ICS code)

HFM code 35 O2 system operating at rich limt, mixture too lean (HHT)
HFM code 36 O2 system operating at lean limit, mixture too rich (HHT)
HFM code 84 Momentary fault in Self-Adaptation of closed throttle speed/partial load (HHT)

As you can see, HHT provides more information.

www.alldatadiy.com is a good source

I still don't . . .
 

see where that car has 84 DTCs?? Also DTC 35 is "AIR pump switchover valve and/or electromagnetic AIR pump clutch".

HHT code 35 coupled with 84 indicate MAF, but before replacing , check for vac leaks at SOV feed hose in front of engine . plastic hose breaks/common leak point. Also , check for leaking fuel at fuel pressure regulator. [ remove vac hose and look for fuel at port]
Your car is at rich limit , running lean. [ HHT 35]
84 is HHT code for adaptation limit at idle. This is an adaptation code not retrievable w/flash.
The code 35 is a digital sub code [ the actual HHT readout will be 035] for a code 13 on pin #8 with Flash code tool.
As Zaf has pointed out , HHT codes are digital on your car and go up to 208. These are refined pre OBD2 codes that breakdown the flash codes to exact trip conditions in a digital format. Only HFM/SFI has this neat little feature on 124s.

[ ie , your code 13 will be broken down to either a rich or lean condition and moitored with digital fault storage, allowing for more refined diagnosis..
..but for crude fault tracing, the led/sw tool is worth making to get to the other modules..

Jim, I believe that the codes listed are FROM the HFM ECU! Not from the diagnostic module! HFM DIGITAL codes go all the way to 144 on a M104 engine.

Thanks for your help so far
 

Thanks for your help so far. My vehicle has a 16 pin diagnostic connector.(image attached) It apperars only pins 1, 3, 6, 7, 8, 10, 14, and 16 are used. where can I find a "lookup table" for interpreting pin numbers and associated blink codes? I am willing to buy a MB diagnostic manual--can anyone suggest a source?

Thanks,

J. m. van swaay

Here's the pin-map . . .
 

. . and the functions associated with those pins;
1 = Ground
3 = Diagnositic Module
6 = SRS
7 = A/C
8 = HFM/SFI
10 = TN Signal
14 = EA
16 = Voltage, Ignition ON (Circuit 15)

Flash codes [ NOT HHT codes]. do not confuse the two..

http://www.peachparts.com/shopforum/tech-help/107630-e320-16-pin-dtc-charts-inc-pin-8-pin-14-a.html