The R231 SL (2013-2020) is a complex GT with retractable hardtop and active suspension that demands diligent maintenance. The M276 3.0T V6 and M278 4.7T V8 both have serious oil consumption and bearing wear issues when neglected, plus significant transmission cooler and mount failures.
Symptoms: Burning 1+ quart per 1,000 miles, Blue smoke on cold start or acceleration, Rod knock or low-end engine rumble, Low oil pressure warning at idle, Metal shavings in oil filter during changes
Fix: Root cause is often inadequate oil change intervals causing piston ring carbon buildup and worn rod bearings. Rings-only job requires 18-24 hours labor. Full bearing replacement (rods and mains) adds another 8-12 hours. Many owners opt for short block replacement at 28-35 hours labor when multiple cylinders affected or crank is scored.
Estimated cost: $6,500-18,000
722.9 Transmission Oil Cooler Failure
Common · high severity
Typical onset: 70,000-110,000 mi
Symptoms: Pink or milky transmission fluid on dipstick, Transmission slipping or delayed engagement, Coolant mixing with ATF (cross-contamination), White smoke from exhaust if coolant enters transmission, Transmission overheating warnings on dash
Fix: Internal cooler in radiator develops leaks allowing coolant and ATF to mix, destroying the transmission if not caught early. Requires radiator replacement (4-6 hours) plus complete transmission flush and filter service (3 hours). If contamination progressed, transmission rebuild or replacement adds 16-22 hours.
Estimated cost: $2,800-12,000
Transmission Mount Collapse
Common · medium severity
Typical onset: 50,000-90,000 mi
Symptoms: Loud clunk when shifting from Park to Drive/Reverse, Excessive drivetrain shudder during acceleration, Vibration felt through center console at idle, Visible transmission sag when inspected on lift
Fix: Hydraulic transmission mount fails prematurely, especially on V8 models. Requires subframe partial drop for access. Factor 4-5 hours labor for mount replacement plus alignment check afterward.
Estimated cost: $800-1,400
ABC Active Body Control System Leaks & Pump Failure
Occasional · high severity
Typical onset: 80,000-120,000 mi
Symptoms: ABC warning light with 'Vehicle rising' or 'Too low' messages, Car sits noticeably lower on one corner, Hydraulic fluid puddles under vehicle, Whining or grinding noise from ABC pump, Rough ride with loss of adaptive damping
Fix: ABC struts develop seal leaks ($1,200-1,800 each, 3-4 hours per corner). Pump failure requires 6-8 hours and often coincides with contaminated fluid from leaking struts. System holds 7+ liters of special fluid at $40/liter. Once one component fails, cascade failures are common within 12-18 months.
Estimated cost: $3,500-9,000
Vario Roof Hydraulic System Failures
Occasional · medium severity
Symptoms: Roof operation stops mid-cycle with error message, Slow or jerky roof movement, Hydraulic fluid leaks in trunk area, Roof won't latch or unlatch electronically, Clicking or grinding from roof mechanism
Fix: Complex 3-piece folding hardtop uses hydraulic cylinders, electric motors, and multiple sensors. Common failures include hydraulic pump (5-7 hours), individual cylinders (3-4 hours each), and limit switches. Diagnosis alone can take 2-3 hours due to system complexity. Roof must be manually secured if failure occurs while open.
Estimated cost: $1,800-5,500
Airmatic Air Suspension Compressor & Line Failures
Occasional · medium severity
Typical onset: 70,000-110,000 mi
Symptoms: Compressor runs constantly (loud from right rear), Vehicle sags overnight or after sitting, Airmatic warning with fault codes, Hissing sound near air struts, Inability to raise vehicle to normal height
Fix: Compressor relay and valve block fail first (3-4 hours), followed by air struts themselves (2.5-3 hours per corner). Air lines crack at fittings. Many owners convert to coil springs ($2,500-3,500) to avoid ongoing air suspension costs, but lose ride height adjustment.
Estimated cost: $1,500-4,800
Fuel Filter Clogging & High-Pressure Pump Issues
Occasional · medium severity
Typical onset: 60,000-100,000 mi
Symptoms: Hard starting especially when hot, Intermittent rough idle and misfires, Loss of power under acceleration, P0087 fuel pressure too low codes, Engine stalling at stops after highway driving
Fix: In-tank fuel filter (not serviceable separately) clogs if fuel quality is poor. Requires fuel pump module replacement at 4-5 hours labor. High-pressure pump on engine (M276/M278) can also fail, requiring 6-8 hours due to location under intake manifold. Both issues often misdiagnosed as ignition problems initially.
Estimated cost: $1,200-3,200
Owner tips
Change engine oil every 5,000 miles maximum with MB 229.5 spec — never stretch intervals despite what maintenance computer says
Inspect transmission fluid color every oil change; pink/milky means immediate cooler attention needed
Budget $2,000-3,000 annually for suspension system maintenance (ABC or Airmatic) after 70k miles
Check roof operation monthly and lubricate mechanism every 6 months to prevent expensive hydraulic repairs
Use only Top Tier fuel to minimize direct-injection carbon buildup and fuel system issues
Beautiful GT with serious complexity and expensive failure modes — only buy with comprehensive service records showing religious oil changes and suspension maintenance, and budget $3-5k annually for repairs after 60k miles.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.
Fitment notes: Located in trunk; AGM required for stop-start system and high electrical demands
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Every control module on the 2013-2017 Mercedes-Benz SL — where it lives, replacement time, and what it takes to program a replacement. Modules marked dealer / factory tool won't work after a part swap alone — budget for programming.
Active Body Control (ABC)3.5 hr R&Rdealer / factory tool +0.8 hr▸ programming details
📍 Engine bay, right side near strut tower (hydraulic unit with integrated controller)
🔧 Xentry Diagnostics
⚠️ Optional system. Expensive component. System bleeding, calibration, and ride height learning required. SCN coding mandatory.
Transmission Control Unit (TCU)2.5 hr R&Rdealer / factory tool +0.7 hr▸ programming details
📍 Transmission bell housing, driver side
🔧 Xentry Diagnostics
⚠️ 7G-Tronic Plus or MCT transmission. Requires transmission drop. SCN coding and extensive adaptation required.
Climate Control Unit (CCU)2.2 hr R&Rdealer / factory tool +0.4 hr▸ programming details
📍 Dashboard, center behind climate control panel
🔧 Xentry Diagnostics
⚠️ Automatic climate control. Dash removal required. Adaptation and calibration required after replacement.
COMAND Online Head Unit (COMAND NTG 4.5/4.7)1.8 hr R&Rdealer / factory tool +0.5 hr▸ programming details
📍 Dashboard, center stack behind head unit
🔧 Xentry Diagnostics
⚠️ Integrated navigation, audio, vehicle settings. SCN coding required for full feature activation. Hard drive common failure.
Electronic Stability Program Control Unit (ESP)1.5 hr R&Rdealer / factory tool +0.5 hr▸ programming details
📍 Under driver/passenger seat, mounted to seat frame
🔧 Xentry or Autel MaxiSys
⚠️ Separate modules for driver and passenger. Memory function and massage seat adaptation required.
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 2016 Mercedes-Benz SL 4.7L Turbo V8 and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years.