2002 MERCEDES-BENZ CLK55 AMG C208

Typical onset: 80,000-120,000 mi

Symptoms: rough idle and misfires, check engine light with multiple cylinder misfire codes, oil leaking onto connectors from valve cover area, brittle, cracked insulation on harness

Fix: Both engine wiring harnesses (front and rear) deteriorate due to heat and oil exposure. Replacement requires 8-12 hours labor depending on harness routing and connector condition. OE Mercedes harnesses are best; aftermarket failures are common.

Estimated cost: $2,000-3,500

Typical onset: 60,000-100,000 mi

Symptoms: transmission fluid leaking at radiator connections, pink milkshake in coolant reservoir (cooler rupture mixing fluids), transmission slipping or delayed engagement after coolant contamination, transmission overheating

Fix: The integral transmission cooler inside the radiator fails, or hard lines crack at connections. If fluids mix, the transmission is toast and needs a full rebuild or replacement (add $3,000-5,000). Preventive replacement of cooler lines and external cooler upgrade is 3-4 hours.

Estimated cost: $800-1,500 (cooler/lines only); $4,000-8,000 if transmission contaminated

Typical onset: 100,000-150,000 mi

Symptoms: metallic knocking or ticking at idle, low oil pressure warning, metal shavings in oil, catastrophic rod knock or seized engine

Fix: Neglected oil changes or extended intervals allow sludge buildup, starving balance shaft bearings and rod bearings. Once knocking starts, the engine needs a full rebuild: pistons, rods, bearings, balance shaft, machine work. Plan 30-40 hours labor for a proper rebuild or 12-15 hours for a used engine swap.

Estimated cost: $8,000-14,000 (rebuild); $5,000-8,000 (used engine swap)

Typical onset: 70,000-110,000 mi

Symptoms: harsh or delayed shifts, clunking on acceleration or deceleration, transmission slipping between gears, check engine light with transmission codes

Fix: The 5G-Tronic transmission's conductor plate (wiring harness inside the valve body) fails due to heat and fluid contamination. Sometimes just the mounts collapse causing harsh engagement. Conductor plate replacement is 6-8 hours with fluid and filter service. Mounts alone are 2-3 hours.

Estimated cost: $1,200-2,200 (conductor plate); $400-700 (mounts only)

Symptoms: no-start condition, stalling while driving, intermittent starting issues when engine is hot, check engine light with crank sensor code

Fix: The crank position sensor fails without warning, leaving you stranded. Common failure point on M113 engines. Replacement is straightforward, 1-2 hours labor, but requires getting under the car. Always carry a spare if you daily drive one.

Estimated cost: $250-450

Typical onset: 80,000-120,000 mi

Symptoms: hesitation or stumbling under hard acceleration, difficulty starting when fuel tank is low, loss of power at high RPM, fuel pump whine from rear of car

Fix: The in-tank fuel pump weakens over time, and the inline fuel filter clogs if not replaced every 30-40k miles. Pump replacement requires dropping the tank, 3-4 hours labor. Filter is 1 hour and should be done preventively.

Estimated cost: $600-1,000 (pump); $150-250 (filter)

Typical onset: 60,000-100,000 mi

Symptoms: clunking over bumps, steering wander or vague on-center feel, uneven tire wear on inside edges, vibration at highway speeds

Fix: The lower control arm bushings (front and rear positions) deteriorate and cause alignment issues. Mercedes doesn't sell bushings separately, so you replace the entire control arms. Plan 4-5 hours for both sides with alignment.

Estimated cost: $1,000-1,600