Hi all, I am new in this forum and I hope I would be able to get help from you guys here.

I have trouble starting my 1995 W202 C280. On occasions, the engine could not be started but instead the cranking sound from the engine could be heard and both the infrared lights (red & green) on the rear view mirror will start to flash alternatively. There are power coming through the car though the lights, stereo etc are working. I have to keep turning the ignition and the sound of the cranking keeps occurring. Eventually I gave up and took out the key and waited in the car for about 2-5 minutes and then the car would start up back to normal as if nothing had happened.

This problem doesn’t happen all the time but happens unexpectedly, say that I’m going to the bank or restaurant for 10 mins and return back to the car and this starting problem will occur; leaving me to wait in the car for 5 mins before it could start again.

Anyone has encountered this problem in their 1995 C280 W202? I have replaced:
- New keys
- New car battery
- A voltage regulator (for the alternator)
- IFZ Control Module

I have done these replacements and the problem still occurs! This has been going on for 7 months now ever since I had installed a new ECU. The MB dealer don't even know what is the cause.

I would really appreciate any comments from you guys?

This is the result i got the the readings in the HTT .

Any ideas?

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have you replaced the batteries in the electronic key? have seen this problem before and is usually flat batteries or dead key. try using your spare key for a while this may help to diagnose if its a key fault.

Yes I have done that, even to all my existing keys. But this only apply when both lights (red & green) are flashing at the same time.

Mine existing problem has both lights flashing alternately....... and the engine could only crank...

when you have both lights flashing alternately and the engine is cranking but wont fire it means that eng control unit has either wrong or no can signal from Ifz. basically your key is coded to the Ifz control unit and when you put your key in the ignition the Ifz receives that code and verifies it, if it is a matched code the Ifz will permit the engine control unit to function, this signal is sent via the can data bus. i have found that sometimes if you turn the key too fast it will create this exact problem, I assume the coded key cant react fast enough hence Ifz sends no can signal to eng control unit and you get locked out for X amount of time. try turning the key slower to allow for all that data to be processed.

Thank you so much for your input Ozzy!

Your feedback is one of the most convincing ones I had for these 4 months!

So when the lights flash alternately, it means the ECU has no/wrong signal from the IFZ? Because I have recently replaced the IFZ Control Module and it didn't seem to help.

As of yesterday, the MB dealer has re-ordered a (coded) new key and new (coded) IFZ control module again for a another trial/test.

Apprieciating and awaiting your comments..

Usually when attempting to start the car I don't turn the key fast at all; I usually, leave at position 2 (ON) until the SRS lights go off and then I start the car. But on occasions when I am in position 2, the lights started blinking alternately, from there I knew there is no need to start the car as it will only crank but just wait for 5 - 10 mins again.

Do you think the IFZ Control Module and key is the cause of this fault?

the IFZ module is most likely the cause of your concern, it is responsible for two things, a; infrared remote central locking. b; drive authorization system (das2). looking at your test printout you have CAN: no reception from IFZ. this can be caused by three problems A; faulty IFZ control module B: faulty transponder coil (serves as the data link between the key and IFZ module) C: faulty key. check the part number on the IFZ module it must be 210 820 32 26 or greater such as 210 820 32 27. unfortunatly this concern can be hard to diagnose as HHT (hand held tester) has very limited funtion unlike its replacement STAR DIAGNOSIS where you can test all control modules from about 1997 on. (about the same time they went to das3 electronic key). let me know how it goes with the new IFZ and key, in the meantime i will endevour to delve into the archives for more information.

Thanks for the reply Ozz,

1. 1.1 My old IFZ part number was 210 820 21 26

1.2 The existing one is 210 820 62 26

1.3 I do not know what is the part number on the next one that is being manufactured and eventually shipped here.

2. A) Faulty IFZ Control Module - There's a possibility it could be faulty (again)
B) Faulty Transponder coil - Something new to my knowledge
C) Faulty key - This suspicion can be eliminated, I have 3 keys and a 4th one coming soon.

2.1 What about the printout CAN: TRANSM. From HFM N3/4 Faulty
Do you know what this means? Or is it a common printout whenever there is a fault caused other components?

Sincerely thanking you for your comments.

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looking at your original part number i would have said you definately need to replace the IFZ as it would be the original module and is surprising it hasn't been replaced sooner, since you have replaced the IFZ and keys i'm starting to think you have a problem elsewere, either in the transponder coil (surrounds the ignition/starter switch) but i doubt, as this would cause fault code IFZ locked out?? or maybe the problem is with the CAN data wires, if you pull the CAN wires from IFZ and try to start the car and then check for fault codes this is what you get: CAN: no reception from IFZ. when you take your car back to the MB dealer ask the tech to check the CAN wires (Controller Area Network) and if it still has connectors on that CAN line get them cut out and have them soldered directly (a lot of CAN faults are caused by faulty connectors) as for the first fault CAN: TRANSM; from HFM n3/4 faulty. i can't really say, it could also be a CAN problem, this needs to be rechecked by your benz tech, if it has reoccured since you last had your car in (they should have cleared all fault codes and retested) then you need to start looking at CAN wires and their connectors. good luck

Thanks for the feedback Ozz!

1. 1.1 These two items were replaced in a different time. The new sets are coming in together and i assumed that they (MB Dealer) will synchronise these 2 simultaneously. Do you think it makes any difference?

2. 2.1 Yes, this simulation was performed right in front of me, that's when the MB Technician concluded that the old IFZ 210 820 21 26 was faulty and replaced a new one 210 820 62 26 (but it did not solve)

3. 3.1 So you think this has nothing to do with the HFM being faulty (Just a suspiscion)? All drivability performance are normal though.

I am sincerely appreciating your efforts and kind knowledge and especially making time to help me with my prolong problem.....

unfortunately it doesn't make any difference as the IFZ has to be initialized to the keys anyway, once it has been initialized it is no longer permissible to install the old control module (even for testing). otherwise malfunctions can occur in both control modules.
The part number on your new IFZ is the current number, this will be the same on the next IFZ.
hmm, could your problem be the HFM?
why was the HFM replaced? is the CAN signal getting to the HFM but it's not being recognised? has the CAN connector on the HFM been checked for correct fitment? i hope this may help

Thank you for your posts Ozz,

The reason why the HFM was replaced because it was misfiring whenever I tried to accelerate so therefore the workshop concluded that the HFM was faulty.

After the replacing this new HFM, everything was running smoothly except on the 2nd day after the installation, this problem started happening. But it went on intermittently despite going back to the workshop to reset the HFM.

Just 2 weeks ago, the dealer took my car in and changed the codings in the HFM and the problem happened again; so therefore DC at Germany advised to replace the keys again and IFZ under warranty. What kind of fault (if there is any) in the HFM cause this kind of intermittent starting failures?

There is another 1995 W202 C280 that was having the same symptoms as mine after the installation of a new HFM last 2 months and the dealer changed the codings as well on the same day he input into mine, there has no complaint from that owner (yet?) Any clues?

Its not the IFZ that prevents the engine from starting its the HFM, the HFM is always locked until it recieves a CAN message from the IFZ, so as soon as you turn your ignition on, the HFM is powered up and then it waits for transmission on the CAN data bus.
The DAS infrared control module (IFZ) evaluates the transponder data transferred and, if valid, releases the engine control via the CAN data bus.
now if the key, transponder coil and IFZ were all working as they should and validation is then put onto the CAN data bus, then the IFZ has done everything it needs to do, from here on its up to the CAN data bus to deliver validation to the HFM, but if it gets to the HFM and the HFM wont accept validation (fault in HFM) the engine will not start.
As far as coding the HFM, this is refering to version coding i.e: what eng, what transmission, what body type, what country etc. when a new control unit is fitted these codings are directly transfered to the new control unit, If HHT (hand held tester) can't communicate with the control unit, you would then have to enter codings manually. these codings are generally YES/NO options. The IFZ would not be part of version coding because its not an option.
I realise this is all a lot to take in and understand but hopefully it helps

Thank you for your answers and for your patience Ozz,


Please pardon my ignorance but I am really learning a lot in depth knowledge from you;

Is the CAN data bus the wiring harness between the IFZ and the HFM or a particular part in the car that could be check for faults and replaced?

Thank you.