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Solved: Mercedes C220 AMG Sport Multiple System Fault

Nothing’s worse than driving around with a warning light on your dashboard, never mind having four of them flashing in your face.

When Mr E brought his car to us at Donnellan Autos, his Mercedes C220 AMG Sport had a few problems.

His car showed multiple warnings, ranging from a faulty control unit to a more worrying Airbag System Failure.

Imagine if Mr E had been in an accident, the airbag wouldn’t have worked as it should, which could have been life-threatening.
Our expert technicians had their work cut out, but they love a challenge.

What we found

Upon the initial inspection, it appeared there was a miscommunication between the car’s operating system and the warning light system.

The error codes were:

  • A207/B2207
  • A761/C240300
  • 520201/C120201
  • 520400/C120400

These probably don’t mean much to you. But, to our Mercedes specialists, it paints a picture of your car, helping us find and fix any issues.

At Donnellan Autos, our technicians are trained to evaluate every car using a 15 step diagnostic process. Doing so guarantees we get to the root of the problem quickly, saving you time and money.

It only took 72 hours to identify the faults, source, and replace the necessary parts.
While you might be thinking three days is a long time, Mr E’s car was a complex job. Most garages would have your car off the road longer.

Luckily, our expert Mercedes technicians deal with these issues daily; they’re quick and efficient. In most cases, your car is back on the road in less than 24 hours.

With Mr E’s C220, the error codes pointed us in the right direction. But, the 15 step process ensured we didn’t miss anything.
While checking over the car, our specialists discovered the airbag module needed replacing as it wasn’t sending or receiving the signals it should. This prevented the airbag from knowing when to work.

The new airbag module was sourced, ordered, and replaced before any further inspections.

As a local Mercedes specialist, we only use genuine or high quality parts in every repair. This guarantees your car runs as smoothly as the day you bought it.

The last thing you want is cheap low-quality parts installed; they won’t last long, and before you know it, you’re back in the garage with more problems.

We’re not like a lot of garages though. We don’t buy cheap parts. We believe you deserve the best quality service from the minute you drive in, to the second you drive out.

Once the Mercedes C220 had the new module installed, our technician discovered a secondary problem. Something which non-Mercedes specialists might have missed.

Solving The Issue

Fortunately for Mr E, the 15 step procedure led our technician to find a broken pyrofuse.

The pyrofuse is part of the protective system which alerts the airbag if you’ve crashed. It’s the last thing you’d want to be broken on your car.

A closer inspection showed the pyrofuse had been broken during a battery refit.

Whoever fitted the battery failed to notice they’d damaged the connection. It’s why our extensive procedure is in place; to ensure minor errors don’t go unchecked.

Now we knew the root cause; the replacement parts were ordered, installed, and retested.

You know what happened next? – No more warning lights.

Hey presto, Mr E’s car ran as smoothly as a German car should.

He was over the moon to have his C220 AMG back in working order. He was even happier when he saw our price, which was under what a Mercedes dealership would charge.

Donnellan Autos likes to give its customers great value and a top tier service.


Mr E’s airbag warning lights were a worrying problem. A malfunctioning airbag is one of the last things you want your car to have.
Fortunately, our Mercedes specialists at Donnellan Autos spotted several issues using our 15 step diagnostic process. Each problem was quickly solved, and Mr E’s Mercedes C220 AMG Sport was back on the road three days later.

No warning lights, no fault codes, and no expensive bill at the end.

If your Mercedes needs a check over, give our experts at Donnellan Autos a call. Our team love to help.

Call us on 091 792474 and book your Mercedes for a premium service without paying through the nose.

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