1994 CL420 (M119) – EFP faults 096 / 224 + ASR 030 CAN error – S29/3 OK in live data

[ESXX]

Hi everyone,

I have searched the forum but could not find a case with the exact combination of symptoms I am experiencing, so I decided to ask for help.

I am working on a Mercedes CL420 (M119 with E-GAS / EFP module N4/1) and I am chasing a persistent limp mode issue.

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Symptoms:

• ABS light comes on immediately with ignition ON
• Vehicle goes into limp mode
• Throttle response is limited

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Fault Codes:

From EFP (N4/1):

• 096 – Starter lockout and reversing lamp switch (S16/3)
• 224 – Idle speed contact switch (S29/3)

From ASR:

• 030 – CAN: No reception from EFP (N4/1) or fault in EFP

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Work already performed:

• ETA (M16/1 throttle actuator) professionally rebuilt (Kurth Classics, Germany) and confirmed fully functional
• Wiring visually inspected (engine bay + accessible areas)
• Extensive live data monitoring performed
• Transmission range recognition (S16/3 / NSS) works correctly in live data
• Reverse lights function correctly
• No obvious issues with throttle linkage or mechanical setup

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Testing / Measurements:

S29/3 (idle speed contact switch):

• Measured directly with multimeter
  • Pedal NOT pressed → open circuit (infinite resistance)
  • Pedal pressed → approx. 1 kΩ
• Values are stable and repeatable

Live data:

• S29/3 switches state immediately and consistently when pedal is pressed
• Signal appears logically correct at all times

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Additional observations:

• M16/1S2 (idle switch inside ETA):
  • Generally behaves correctly
  • Occasionally flickers ON/OFF briefly (approx. every ~20 seconds with ignition ON)
  • I have seen this mentioned elsewhere as possibly normal behavior
• No obvious mismatch between S29/3 and M16/1S2 during normal operation
• Gear recognition (S16/3) appears correct in live data

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Key question:

Given that:

• ETA is rebuilt and confirmed OK
• S29/3 measures correctly and behaves correctly in live data
• S16/3 (NSS) appears correct
• CAN fault (030) is present

Is it possible that the E-GAS / EFP module (N4/1) itself is faulty?

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Or alternatively:

Has anyone seen a case where:

• all signals appear correct in live data
• but faults are still triggered due to wiring issues, grounding problems, or internal EFP logic faults?

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I can also perform resistance measurements directly at the EFP connector if needed.

Any ideas, known failure patterns, or specific diagnostic steps would be greatly appreciated.

Thanks in advance!

 

[gerryvz]

Moving to off-topic discussions forum as this thread does not pertain to the W124 chassis nor the M119 with LH fuel injection.

Edit: This car does have the M119 with LH-SFI.

 

[gsxr]

ASR fault 030 is a generic "ghost" code that always appears with limp mode. Ignore that.

From what you describe, it sounds like the mechanical throttle linkage is not adjusted properly, resulting in the ETA idle switch not triggered at idle. Usually this is due to the throttle cable pulling on the linkage slightly at idle, OR one of the linkage rods set to the wrong length. This will cause immediate limp mode when the engine is started, along with ASR fault light.

However, if the live data shows otherwise, and the switches are in sync... I'm stumped. I would try a different, known-good E-GAS module next. They are plentiful and cheap for the 140 chassis.

Do the 3 values for S29/3, M16/1s2, and M16/1s1 all reverse from OFF/ON/OFF to ON/OFF/ON when you press the accelerator pedal off idle, and return to normal idle position when the accelerator pedal is NOT pressed?

Welcome to the forum!

 

[ESXX]

Thanks for the detailed reply, this is very helpful.

I will verify the exact relationship between the three signals:
S29/3, M16/1s2 and M16/1s1 as you described (OFF/ON/OFF → ON/OFF/ON).

So far in live data they appear logically correct, but I will double-check specifically for perfect synchronization and any brief mismatch.

If everything checks out, I will try swapping the E-GAS (N4/1) module next.

I will report back with the results.

 

[ESXX]

Hi again,


I did some additional testing and recorded a short video to better illustrate what is happening.


In the video:

• At the beginning, the engine is at idle
• Then I apply throttle (you can clearly hear when I press the accelerator)
• Based on the engine sound, it is easy to distinguish idle vs throttle input

The goal was to show how the switches behave in real time.

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Additional measurements (multimeter at EFP connector)​

I also measured the ETA internal switches directly at the E-GAS (N4/1) connector, so this includes both the switches and the wiring.

M16/1s1:​

• Throttle closed → open circuit (∞)
• Throttle open → ~342 Ω
• Switching point occurs exactly when the throttle plate starts to move mechanically

M16/1s2:​

• Throttle closed → ~333 Ω
• Throttle open → open circuit (∞)
• Again, switching occurs right at the initial mechanical movement of the throttle

Based on this, I assume the ETA and wiring are working correctly, and the switch logic appears to be functioning as designed.

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Remaining issue​

What seems strange is how these values are interpreted in the E-GAS live data.


Even though:

• The switches measure correctly with a multimeter
• The switching points are mechanically correct

The values shown by the E-GAS module do not always behave logically or consistently.

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Question​

Has anyone seen a case where:

• The switches (S1 / S2) test perfectly with a multimeter
• Wiring is OK
• But the E-GAS module still misinterprets the signals and causes faults / limp mode?

At this point I am starting to suspect the E-GAS (N4/1) module itself, but I would appreciate any feedback before replacing it.

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Thanks in advance for any ideas

 

[gsxr]

After clearing fault codes, and then after limp mode / ASR light comes back on... do you still have the same 2 fault codes stored?

• 096 – Starter lockout and reversing lamp switch (S16/3)
• 224 – Idle speed contact switch (S29/3)

Are there any other fault codes (still ignoring ASR 030)?

Some additional diagnostic information is in the Diagnostic Manual at the link below, however I'm not sure if this will help or not:

https://manual.startekinfo.com/manual/JSP/e3/6_2/m23.jsp

 

[ESXX]

Hi,


Yes – after clearing all fault codes, both faults return immediately as soon as I start the engine:

• 096 – Starter lockout and reversing lamp switch (S16/3)
• 224 – Idle speed contact switch (S29/3)

There are no additional fault codes (aside from ASR 030, which we are ignoring as suggested).

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Additional observation (ABS light)​

The ABS warning light also comes on immediately and never goes out:

• With ignition ON → all dashboard lights come on (normal)
• After starting the engine → all lights go out except ABS, which stays on permanently

The ABS light does not go out even for a moment after engine start.

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So the situation is:

• Fault codes return immediately (no delay, no driving needed)
• Limp mode is present right away
• ABS light is permanently on from startup

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Any ideas based on this behavior?


Thanks

 

[gsxr]

I am confused about the immediate code 096 when you have confirmed in live data that the gear position indicators are correct for all gear positions. And, the same for code 224 since you have confirmed both the switch and live data appear correct (no fault).

I would try a spare E-GAS module if possible, ideally a known-good unit from another 140 chassis with ASR (can be either 4.2L or 5.0L). I doubt the E-GAS module is defective but it would help to rule that out.

 

[ESXX]

Hi again,

I finally managed to get another E-GAS / EFP module (used but known good), and after installing this second module the situation changed significantly.

Now the ABS light is still ON, but I only have ONE remaining fault code:

096 – Starter lockout and reversing lamp switch (S16/3)

Fault 224 is now completely gone with the replacement E-GAS module.

After this, I checked the transmission range live data once again very carefully, and I discovered something VERY interesting:

When the gear selector is in:

• P or N → the live data incorrectly shows position “F”
• D / R / 2 / 3 → the live data shows the positions correctly

This seems like a huge clue.

At this point I am starting to suspect that the Neutral Safety Switch / transmission range switch itself is faulty.

The part number appears to be:

A0005456206

My current theory is that this incorrect P/N recognition is what keeps triggering fault 096 and probably also causes the ABS warning light and limp mode behavior.

What I found so far is that this switch is EXTREMELY difficult to find — it seems to be discontinued and unavailable almost everywhere.

Does anyone know:

• where this part can still be purchased,
• if there is a compatible replacement,
• or if it can be rebuilt/repaired?

Any help would be greatly appreciated

 

[gsxr]

That's great progress! And yes, your NSS is either mis-adjusted, or faulty... and it's the reason you are getting code 096.

A0005456206 went NLA a number of years ago and is almost impossible to find new / NOS.

Kurth offers a replacement "on request", details here.

Or, you can take your old one apart and repair it, as shown here.