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Mercedes Benz Cla Problems & Known Issues

The most common Mercedes Benz Cla problems ranked by severity — what to watch for, what it costs to fix, and what happens if you ignore it.

Generations

C117 — First Generation
2013–2019
1.6 Turbo, 2.0 Turbo, 1.8 CDI, 2.1 CDI
C118 — Second Generation
2019–2024
1.3 Turbo, 2.0 Turbo, 2.1 CDI

Top issues to watch for

The most serious Mercedes Benz Cla problems ranked by severity. We track 5 known issues — here are the ones you need to know about first.

Major
Excessive brake pad wear (C117/C118)
C117, C1182013–20240k–120k miles
MOT data shows CLA models fail brake pad thickness tests at up to 15.3 times the national fleet average, particularly on 1.6-litre petrol variants at low mileage. The issue affects all engine variants and appears across all mileage bands from new cars to high-mileage examples. This suggests either undersized brake components for the vehicle weight, aggressive pad compounds, or brake system design issues causing uneven pad wear patterns.
What happens if ignoredBrake pads worn to metal backing plates will score brake discs requiring expensive disc replacement alongside pad renewal. Complete brake failure is possible if pads wear through entirely. Typical pad and disc replacement costs £400-800 depending on whether front axle only or full vehicle renewal is required.
Independent garage
£150–£400
Specialist
£200–£500
Main dealer
£300–£800
Parts only
£80–£300
Major
Brake fluid loss (C117/C118)
C117, C1182013–202420k–100k miles
MOT data shows CLA models fail brake fluid level tests at up to 11.5 times the national fleet average, particularly affecting 1.3-litre petrol variants in the 40,000-60,000 mile range. This pattern suggests either brake system leaks developing at specific service intervals, brake caliper seal degradation, or brake fluid consumption through normal pad wear being unusually high on this model.
What happens if ignoredLow brake fluid reduces braking performance and can lead to complete brake system failure. Air entering the brake system through leaks causes spongy pedal feel and extended stopping distances. Brake system repair costs typically range from £200-600 depending on whether the issue is brake line corrosion, caliper seal failure, or master cylinder problems.
Independent garage
£200–£500
Specialist
£250–£600
Main dealer
£350–£800
Parts only
£50–£200
Minor
Suspension joint dust cover deterioration (C117/C118)
C117, C1182013–202420k–150k miles
MOT data shows CLA models fail suspension dust cover tests at up to 7.2 times the national fleet average, particularly affecting 2.1-litre diesel variants from 20,000 miles onwards. The failures span all mileage ranges from 20,000 miles to 150,000+ miles, suggesting either poor-quality rubber compounds in the dust covers or suspension geometry that places unusual stress on the protective boots covering ball joints and bushes.
What happens if ignoredFailed dust covers allow road dirt and water to contaminate suspension joints, leading to accelerated wear and eventual joint failure. While not immediately dangerous, contaminated joints will require replacement within 12-24 months rather than lasting their normal service life. Ball joint replacement typically costs £200-400 per corner.
Independent garage
£150–£300
Specialist
£200–£400
Main dealer
£300–£600
Parts only
£30–£100
Minor
Engine management light illumination (C117/C118)
C117, C1182013–20240k–150k miles
The pattern affects all mileage bands including new cars, suggesting emissions system faults rather than wear-related issues. Common causes on Mercedes diesels include DPF regeneration problems, NOx sensor failures, and EGR valve carbon build-up.
What happens if ignoredAn illuminated engine management light causes automatic MOT failure. Underlying faults can include expensive DPF problems (£1,500-3,000 replacement), NOx sensor failures (£300-600), or EGR valve issues (£400-800). Some faults may trigger engine protection modes reducing power output.
Independent garage
£80–£1,500
Specialist
£100–£2,000
Main dealer
£120–£3,000
Parts only
£50–£1,500

1 more known issues tracked

Including wear items, electrical niggles, and generation-specific problems. Check a specific car to see which issues apply to its age and mileage.

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MOT failure hotspots

Based on DVSA MOT test data. These are the items where the Mercedes Benz Cla fails at a significantly higher rate than the average car.

Any fracture or welding defect on a wheel
Wheels · 0-20k miles
MOT failure rate: 39x the fleet average
Sample: 5,190 tests
Wheel with a loose or missing wheel nut, bolt o...
Wheels · 0-20k miles
MOT failure rate: 22x the fleet average
Sample: 1,152 tests
Window tint too dark
Wipers & Windscreen · 80-100k miles
MOT failure rate: 14x the fleet average
Sample: 9,980 tests
Tyre wear or damage
Tyres · 150k+ miles
MOT failure rate: 12x the fleet average
Sample: 990 tests
Brake fluid significantly below minimum mark
Brakes · 40-60k miles
MOT failure rate: 12x the fleet average
Sample: 5,848 tests
Brake lining or pad worn down to wear indicator
Brakes · 0-20k miles
MOT failure rate: 12x the fleet average
Sample: 19,298 tests

Buying a Mercedes Benz Cla?

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Related

Mercedes Benz Cla reliability FAQs

What are the most common problems with the Mercedes Benz Cla?

The Mercedes Benz Cla has 5 known issues across 2 severity levels. The most common problems relate to Excessive brake pad wear (C117/C118) and Brake fluid loss (C117/C118).

Is the Mercedes Benz Cla reliable?

The Mercedes Benz Cla has 0 dangerous and 2 major known issues. No dangerous issues are tracked, which is a positive sign.

How much does it cost to fix Mercedes Benz Cla problems?

Repair costs range widely. The most significant issue (Excessive brake pad wear (C117/C118)) costs £150–£400 at an independent garage. Minor issues can be under £200. Always get a full inspection before buying.

Which Mercedes Benz Cla generation is most reliable?

The C117 (2013–2019) has the fewest dangerous issues (0). However, condition and service history matter more than generation — a well-maintained earlier car can be more reliable than a neglected newer one.