Mercedes-Benz EIS/EZS Module Repair – Key Not Recognised

Are you experiencing issues where your Mercedes’ key fob isn’t being recognised when inserted into the ignition? This is commonly a sign that your Mercedes’ EIS/EZS module is defective and in need of repair. Thankfully, we’re able to restore functionality to these units within 2-3 working days and with a lifetime warranty included.

Shop Now – Mercedes EIS/EZS Module Repair

EIS/EZS modules are fitted to a wide range of Mercedes-Benz models from the last 30 years. However, those fitted to 2009-2021 models like the W447 Vito, W176 A-Class and W212 E-Class are frequently left in need of repair.

Fortunately, we’re the specialists at restoring functionality to these units. We’ve been remanufacturing automotive control units since 2005 and our defect rate is now as low as 0.49%.

Fill out our short test form today to have your Mercedes’ EIS/EZS module tested and repaired in just 2-3 working days.

What is the Mercedes-Benz EIS/EZS module?
The abbreviations ‘EIS’ and ‘EZS’ refer to the same control module. It’s the black ignition module typically positioned behind the steering wheel, close to the steering column.

You might know already that ‘EIS’ stands for electronic ignition switch, while ‘EZS’ derives from the German term Elektronisches Zündschloss. Often in Mercedes documentation, you’ll find that the EIS/EZS is referred to as an N73 unit.

So, in summary, a Mercedes-Benz EIS, EZS and N73 module refer to the same control module. These units began being used in Mercedes vehicles in the late 1990s, initially featuring in the W210 E-Class and W202 C-Class.

If you own an EIS/EZS-equipped Mercedes vehicle, you’ll know that its key isn’t like that of many other vehicles, it’s actually a black fob-like transmitter. In these systems, the key fob is electronically recognised by the Mercedes’ EIS/EZS module. In millions of other vehicles, it’s standard for a metal key to mechanically turn the ignition barrel, which can be easier to physically manipulate than the electronically controlled ignition lock used by the EIS/EZS. The immobilisation procedure is similar in both systems, as the engine ECU must still receive valid authorisation before allowing the engine to start.

Over the years, Mercedes have continuously developed their vehicle security systems, significantly transitioning from FBS3 to FBS4 in the early-to-mid 2010s. FBS (Fahrberechtigungssystem or drive authorisation system in English) is the immobiliser system used in modern-era Mercedes vehicles. As a result, there are now many iterations of Mercedes EIS/EZS module, which can make sourcing a repair confusing.

Thankfully, no matter the Mercedes model your N73 unit has come from, we’ll gladly take a look at it – just fill out this test form with your fault symptoms.

Mercedes EIS/EZS module faults
Although Mercedes’ EIS/EZS system introduced a significant development in vehicle security technology, these control modules are frustratingly susceptible to failure.

As expected, the most common sign that your Mercedes’ EIS/EZS module is in need of repair is when it no longer recognises the key. For example, when inserting the key fob into a defective EIS/EZS, the ignition lights on the dashboard may not illuminate, the steering lock may remain applied, and ultimately, you won’t be able to start the engine.

Thankfully though, we’ve developed a cost-effective option to restore unit functionality.

Our solution
Rather than purchasing a brand-new EIS/EZS module to resolve the issue with your Mercedes’ key not being recognised, we suggest having your original unit repaired instead. Not only will this save you significant time and money, but you’ll also remain covered by our unlimited-mileage lifetime warranty.

Better still, you won’t need to have your repaired Mercedes EIS/EZS module recoded to your vehicle afterwards, like you would with a brand-new module, saving even more time and money. Send your unit to us today to restore functionality quickly and reliably.

Common failure symptoms:

• Mercedes key not recognised
• Ignition lights don’t come on with the key in the ignition
• Steering lock won’t release
• No start

Test and rebuild:
We test and rebuild control units using state-of-the-art equipment. We even develop our own hardware-in-the-loop rigs in-house.
 
Programming:
You won’t need to have the EIS/EZS module recoded to your Mercedes when you receive it back from us via an insured courier. This is because programming information is left untouched throughout our process.
 
Quality:
Our strict quality-assurance procedures are part of the reason our services are used worldwide by thousands of industry specialists. Currently, our company-wide defect rate stands at just 0.49%.

Warranty:

Lifetime unlimited mileage*

How do I get my unit rebuilt?

To pay for the rebuild click the Shop Now link above, select your part number and click: Get yours rebuilt.

Print the payment/booking confirmation email.

Package the EIS/EZS module inside a sturdy box with plenty of packaging material and make sure you include your confirmation email in the box.

Send us your package by tracked courier (the shipping instructions are on the confirmation email).

Once received we will test, rebuild and return your control unit with an unlimited mileage lifetime warranty. If your unit turns out not to be faulty then we will refund your payment less a small testing fee and return shipping.

What if I don’t want to pay up front?

This is not a problem, if you prefer this option then follow these steps:

Fill in and submit this test form.

Print the booking confirmation email.

Package the control module inside a sturdy box with plenty of packaging material and make sure you include your confirmation email in the box.

Send us your package by tracked courier (the shipping instructions are on the confirmation email).

Once received, we will test your unit and call to inform you of the outcome of testing. If your EIS/EZS module is faulty and you choose to go ahead with the rebuild, then we will take payment over the phone using a debit/credit card.

We will then rebuild your N73 unit and return it to you with an unlimited mileage warranty.

If you require further information regarding this Mercedes EIS/EZS module repair then please contact us.