Exhaust Mercedes GLA-Class X156 (2014-2020)

The Mercedes GLA-Class X156, especially diesel models like the 200 CDI 4MATIC or 220 CDI, often face problems with the exhaust flap servomotor (reference M16/57). Positioned mid-exhaust line after the DPF and catalytic converter, this servomotor adjusts the exhaust diameter to create backpressure, enhancing engine torque and response.

Over time, soot, moisture, oxidation, age, and mileage can cause the servomotor to seize, resulting in:

• Check engine light activation
• Limp mode limiting engine RPM to 3000
• Acceleration jerks
• Automatic gearbox stuck in one gear

These symptoms indicate the servomotor's failure or malfunction in controlling the exhaust flap accurately.

Official dealer solutions generally involve replacing the entire mid-section of the exhaust line at a cost between €650–1000 inclusive of tax, since the servomotor is not sold separately.

For a more economical alternative, original Mercedes servomotor units (including bolts and spring) are available from specialised independent parts suppliers, often at significantly reduced prices.

Besides the servomotor, owners might experience:

• Faulty exhaust backpressure sensor – usually fixed by sensor replacement
• Exhaust flap motor failure detected via OBD diagnostic codes indicating a stuck flap
• Unusual noises such as clicking, vibrations, or crackling caused by poor assembly – examples include misaligned retaining rings, missing rubber mounts, or loose bolts causing metal-on-metal contact

These issues can often be resolved with repairs such as tightening linkages, adding felt padding, or correcting assembly errors.

Valuable resources include:

• Specialist blogs detailing servomotor faults and original parts availability
• Mercedes enthusiast forums sharing experiences and DIY fixes for exhaust noises and flap issues
• Community diagnostic posts on OBD fault codes related to exhaust components
• Online garages assisting with locating independent repairers for GLA exhaust issues

Consult these to deepen your understanding, share experiences, and find trusted repair options.

The servomotor controls a valve within the exhaust pipe that reduces the exhaust diameter to generate backpressure. This backpressure improves engine torque and throttle response during certain driving conditions.

• Located after the DPF and catalytic converter in the exhaust line
• Operates by adjusting internal flap position based on engine management commands
• Improves performance and drivability under load

Wear and contamination may cause this component to seize, leading to drivability problems.

For advanced and reliable diagnosis, use an OBD diagnostic tool to check for error codes related to:

• Exhaust flap servomotor malfunction
• Backpressure sensor failure
• Valve motor errors indicating stuck or unresponsive flap

Visual inspection under the vehicle is also recommended to detect mechanical assembly issues causing abnormal noises or vibrations.

Note that similar symptoms and defects are found on related Mercedes models like the A-Class and CLA, sharing the same platform.

To enhance your research, use specific keywords in Google such as:

• "Mercedes GLA servomotor exhaust fault"
• "GLA 200 CDI exhaust noise clicking"
• "GLA exhaust flap error OBD"
• "Replace servomotor Mercedes GLA"
• "Exhaust sport GLA tuning"

Look for technical forums, specialist parts sellers, and video tutorials for visual repair guidance and price references.

When searching for replacement exhaust parts, prioritize:

• Original quality or equivalent high-grade stainless steel components to ensure durability and reliable function
• Parts compliant with European standards and certified by recognized authorities
• Specialist advice and support from trusted distributors experienced with Mercedes GLA exhaust systems

Avoid reconditioned parts and unclear quality sources. Properly installed, high-quality components contribute to safe operation, optimal sound, and engine performance.

For more detailed technical support and purchasing, contact official or reputable suppliers directly.