How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Stan Your Own Question
Stan, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3526
Experience:  Technical support engineer
Type Your Mercedes Question Here...
Stan is online now

I have an S 320 CDI, 2003, chassis WDB2200252A361874.My

This answer was rated:

I have an S 320 CDI, 2003, chassis WDB2200252A361874. My remote central locking has stopped working. From inside the car everything works perfectly via the buttons. Externally the remote key fob does not work, have been to auto electrician and he condemned my key fob. Having bought a new fob from mercedes the new fob works the same as the old fob. The car will however lock on occasions using the infrared side of things, but is intermittant What can you suggest?, if it is the receiver, where do I find it and what does it look like please. Many thanks David Froggatt 


I have paid £27 and in an attempt to get a resolve I have paid a further £21 by pay pal

Hello David,

I'm Shantal and I'm a moderator for this topic.

We have been working with the Experts to try to help you with your question. Sometimes it may take a bit of time to find the right fit.

I was checking to see if you had already found your answer or if you still need assistance from one of the Experts.

Please let me know if you wish to continue waiting or if you would like for us to close your question?

Thank you,

Customer: replied 3 years ago.

No I do not have any resolution to the problem, you help would be most appreciated

Hello David,

Please double-check how the infrared receivers in front doors are working by operating the key fob's buttons right at the receivers (5cm away from door handles)

Make sure that the batteries in the key are new and their voltage checked.

If the infrared is working ok, the rear window amplifier can be faulty. It receives the key's radio signals and converts them into data and then sends the message to the ignition switch.

Click here for the description of the signal receiving function.

Let me know how i can help you more on this.

Best Regards,
Customer: replied 3 years ago.

As stated the infra red is intermitant, it will not lock or unlock the car from either side. Another time you can try one side and fails to work, go to the other side of the car and it will lock or unlock.


The only consistent thing is that no way will it work remotely

Are you sure that batteries are OK in the remote control?
If they are fine, next suspect is the ignition switch, because it processes separately the signal from door control units (IR) and from antenna amplifier( radio remote). If both paths are not working, the only common part is the ignition switch
Customer: replied 3 years ago.

Yes all batteries are ok.


Since ignition switch starts car ok how can I test it for receiving signals for locking or unlocking my car door please?

The only way is to have it checked with Xentry Diagnostics computer. Some independent workshop have this tool, as well as hacking equipment capable to teach in used ignition switch to your car. Dealer would have to order and install a new one for your car
Stan, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3526
Experience: Technical support engineer
Stan and other Mercedes Specialists are ready to help you