The 2015 S63 AMG with the M157 5.5L biturbo V8 is a phenomenal performance sedan when healthy, but suffers from catastrophic engine failure due to defective piston skirt casting—a well-documented issue that can grenade an otherwise pampered motor between 40k-80k miles.
M157 Piston Skirt Failure (Catastrophic)
Common · high severity
Typical onset: 40,000-80,000 mi
Symptoms: Sudden loss of power and violent knocking, Metal shavings in oil, Check engine light with misfire codes, Cylinder wall scoring visible on borescope, Sometimes zero warning before catastrophic failure
Fix: Complete engine rebuild or long-block replacement required. Mercedes issued extended warranty coverage up to 156k miles for affected VINs, but many '15s fall outside that window now. Independent rebuild with forged pistons runs 60-80 hours labor plus machine work. Long-block swap from Mercedes is 35-45 hours but parts cost is astronomical.
Estimated cost: $18,000-35,000
Seven-Speed MCT Transmission Oil Cooler Leaks
Common · medium severity
Typical onset: 60,000-100,000 mi
Symptoms: Trans fluid dripping from bell housing area, Burnt fluid smell after spirited driving, Occasional harsh 2-3 upshift when hot, Low fluid warning on cluster
Fix: Oil cooler lines crack at crimps or cooler itself develops pinhole leaks. Requires trans drop to access properly—about 8-12 hours labor. Often find deteriorated trans mount during this job, smart to replace simultaneously.
Estimated cost: $2,200-3,800
Transmission Mount Collapse
Common · medium severity
Typical onset: 50,000-90,000 mi
Symptoms: Heavy clunk on throttle tip-in or lift, Vibration at idle in Drive, Visible separation or fluid weeping from mount, Driveline shudder during aggressive launches
Fix: The hydraulic mount fails from heat and torque stress. Replacement is straightforward but requires supporting trans—3-4 hours labor. OEM part is mandatory; aftermarket mounts fail within 10k miles.
Estimated cost: $800-1,400
Turbocharger Wastegate Rattle and Failure
Occasional · high severity
Typical onset: 70,000-120,000 mi
Symptoms: Rattling on cold start that disappears when warm, Overboost or underboost codes P0234/P0299, Loss of power above 4000 RPM, Excessive blue smoke under boost
Fix: Wastegate actuator arms wear and rattle, eventually stick open or closed. Each turbo is about 12-16 hours labor due to tight packaging—requires bumper removal, intercooler out, and exhaust manifold work. Often both turbos done simultaneously to avoid repeat labor.
Estimated cost: $6,500-11,000
Airmatic Suspension Strut Leaks
Occasional · medium severity
Typical onset: 60,000-100,000 mi
Symptoms: Vehicle sits low on one corner after sitting overnight, Compressor runs excessively, Suspension warning on dash, Visible oil residue on strut body
Fix: Air struts develop seal leaks, especially fronts. Replacement is 2-3 hours per corner. Compressor often survives if caught early, but if it's been compensating for leaks for months, expect compressor replacement too (add $1,200-1,800).
Estimated cost: $1,800-2,800
Fuel System High-Pressure Pump Failure
Occasional · high severity
Typical onset: 80,000-130,000 mi
Symptoms: Extended cranking before start, Rough idle and hesitation under load, P0087 fuel pressure too low code, Limp mode activation randomly
Fix: High-pressure fuel pump in the valley between cylinder banks fails from contamination or wear. Access requires intake manifold removal—10-14 hours labor. Always replace fuel filter simultaneously and flush rail/lines if metal found.
Estimated cost: $3,200-5,000
ABC (Active Body Control) Hydraulic Line Leaks
Rare · medium severity
Symptoms: ABC warning light with visit workshop message, Green fluid puddles under car, Suspension feels stiff or unresponsive, Pump noise increases
Fix: High-pressure hydraulic lines rust through or develop leaks at fittings. Identify leaking line, replace section—labor varies wildly from 2-8 hours depending on location. Front lines easier; rear lines require exhaust and subframe work.
Estimated cost: $1,200-4,500
Owner tips
Check VIN against Mercedes M157 piston warranty extension—some '15s qualify for coverage up to 156k miles
Do oil analysis every 5k miles to catch piston failure early; aluminum and iron levels spike before catastrophic failure
Use only Mercedes-approved 0W-40 oil and change every 5-7k miles maximum—the M157 is unforgiving with oil quality
Keep trans fluid changed every 40k miles despite 'lifetime' claim—heat destroys MCT fluid fast with spirited driving
Budget $3-5k annually for maintenance and repairs after 60k miles; these are $150k+ cars with corresponding parts costs
Only buy if you have verifiable engine rebuild records with forged pistons or can absorb a $25k engine replacement without blinking—otherwise this is a financial hand grenade.
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: OEM size: 12V 12Ah AGM (MB A 000 982 08 08 / similar backup-battery type) · Location: engine compartment, right/passenger side under a plastic cover near the firewall (main starter AGM battery is in the trunk/under rear seat area) · Purpose: voltage support during ECO start-stop restarts and backup power for critical control units
As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.
Every control module on the 2014-2017 Mercedes-Benz S63 AMG — 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.
Parktronic Control Unit (PTS)0.7 hr R&Raftermarket tool +0.3 hr▸ programming details
📍 Trunk, right side panel
🔧 Xentry/DAS or Autel
⚠️ Sensor calibration required after replacement.
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 2015 Mercedes-Benz S63 AMG 5.5L V8 BiTurbo M157 and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years.