The Mercedes-Benz CLS, launched in 2004, reimagined luxury by blending coupe styling with sedan practicality. But beneath its refined façade lie several mechanical and electrical issues across its three generations: C219 (2005–2010), C218 (2012–2018), and C257 (2019–2023). This guide explores each area in-depth so you can make an informed purchase.
1. Airmatic Suspension Issues
Air suspension failures are among the most frequently reported problems, especially on AMG trims and higher-spec models.
- Symptoms including uneven ride height, constant compressor noise, or dashboard warnings often indicate worn air struts, leaking lines, or valve block malfunctions.
- Many owners opt to convert to standard coil springs to avoid recurring expenses a popular solution supported in multiple user communities.(Reddit)
2. Engine Balance Shaft & Timing Chain Faults
The early petrol engines (M272 and early M273) suffer from balance shaft gear wear, leading to misfires, warning lights, and potentially catastrophic chain failure.
- Later engines post‑2008 feature revised gears that resolved the issue. Look for engine serial numbers to confirm updates.
- Timing chain tensioner failures have also been reported in the M278 V8 engines (found in CLS550/CLS450), contributing to rattling noises and oil contamination of engine wiring.(bestyears.neocities.org)
3. Oil Leaks Around Gaskets & Cooler Seals
Oil seepage is common around rocker cover gaskets, balancer shaft seals, and oil cooler joints especially in diesel models.
- Signs include oil spots on the ground, low oil levels between services, or a burnt oil smell. Early detection and repair are critical to prevent sludge buildup.(CarExamer)
4. Transmission and Speed Sensor Faults
Both the 7G‑Tronic and 9G‑Tronic automatic transmissions can develop shift problems.
- Faulty speed sensors often cause delayed or erratic shifting. There are repair kits for later models, but early gearboxes may require valve body replacement or full gearbox swaps. Regular fluid changes every 50,000–60,000 km help prevent issues.(autocar.co.uk)
5. Infotainment, Sensors & Electrical Glitches
Older CLS models frequently experience COMAND infotainment bugs, sensor malfunctions, and seat/door control failures.
- Systems often freeze, refuse Bluetooth pairing, or fail to register blind spot or window inputs. Later models (post‑2015) show fewer issues following software stability improvements.(CarExamer)
6. Turbocharger & Diesel System Build-up
Diesel variants, particularly those with OM642 V6 engines, are prone to carbon buildup, EGR valve faults, and occasional turbocharger wear.
- Symptoms include black smoke, reduced power or whining under acceleration. Consistent oil changes and proper EGR maintenance help mitigate long-term issues
7. AMG Model (CLS63) Engine Internal Failures
AMG-powered CLS 63 (M156 engine) models have specific high-risk issues:
- Head bolt corrosion can cause coolant-to-oil mixing, leading to engine hydrolock. This issue affected early CLS63 units before AMG updated the bolts in mid-2010.
- Premature camshaft wear creates ticking noises at cold start and worsens over time often traced back to poor lubrication or mismatched valvetrain materials
8. Fire Risk Recall on Third Generation (C257)
Certain C257 models (built between July 2021 and April 2023) are part of a global recall involving a poorly mounted 48‑volt battery ground connection, which could overheat and pose a fire risk. Owners are urged to have their car checked at a Mercedes dealership.(bild.de)
9. Model Reliability by Generation
- C219 (2005–2010): Best avoided in early years; models from 2007 onward show improvements but still need careful inspection. Know whether SBC brakes were replaced.
- C218 (2012–2018): Early units (2012–2014) suffer from timing chain issues and persistent infotainment bugs. From 2015 onward, the CLS450 and later CLS400/CLS550 variants offer significantly better reliability.
- C257 (2019–2023): Regarded as the most refined and trouble-free generation, especially post‑2021 with fewer reported software and electrical issues. Just ensure any recall updates are applied.
Pre-Purchase Checklist
- Inspect suspension height and listen for abnormal compressor activity.
- Listen for timing chain rattle or ticking from engine start.
- Scan the vehicle for fault codes before purchase.
- Verify updated balance shaft gears, timing chain replacements, and Airmatic service records.
- Test COMAND, HVAC controls, sunroof, seats, and ambient lighting in cabin.
- Check for oil leaks around injector lines, cooler seals, and rocker gasket.
Final Verdict
The Mercedes‑Benz CLS delivers an elegant driving experience with its coupe-inspired design, luxury features, and strong performance. Later-generation models (2015 onward) offer reliability and comfort if meticulously maintained. However, early models may require costly upkeep, especially those with air suspension and early engine configurations.
Choose wisely, inspect thoroughly, and prioritize service history your CLS can be a truly rewarding luxury coupe with the right approach.
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