Retarder Fault Symptoms and Causes
Retarder faults usually show up as performance loss, overheating or a warning light. Early diagnosis lets you solve a small repair before it becomes a major overhaul. Here are the most common retarder fault symptoms and causes.
Most common symptoms
Reduced braking force: if the retarder no longer slows the vehicle as before, there is a power loss in the system.
Overheating, burning smell or warning light: coil issues (electromagnetic) and oil/cooling issues (hydraulic) cause overheating.
Noise and vibration: wear in the rotor, bearing or connecting parts can produce abnormal noise.
Likely causes
In electromagnetic retarders, coil failure, cable/connector issues or control-unit errors are common. In hydraulic retarders, oil level/quality, sealing and pump wear are the main causes.
In both types, bearing wear, installation errors and electronic faults can reduce performance. Accurate diagnosis requires inspection by a technical team familiar with that unit type.
Repair or overhaul?
If a single component (e.g. coil, connector, sensor) is faulty, a targeted repair may suffice. If multiple components are worn or the unit is high-mileage, a complete overhaul is more economical and lasting.
KMQ Otomotiv diagnoses Telma and Voith retarder faults and recommends the best solution — repair or overhaul.
Frequently asked questions
- Is the vehicle safe if the retarder is not working?
- As long as the service brakes work, the vehicle stops, but the risk of brake fade increases on long descents. A retarder fault should be fixed as soon as possible.
- How long does retarder diagnosis take?
- Diagnosis is usually quick. At KMQ Otomotiv branches, the technical team responds quickly with the right part and solution.
Request a quote — keep your fleet on the road.
Send us your requirement; our technical team responds within 24 hours with the right part and solution.