Porsche 718 Cayman & Boxster Common Problems

by Ezekiel Lee September 23, 2025

Porsche 718 Boxster & Cayman Common Problems: What Owners Should Know

1. Water Pump Failures & Cooling System Weaknesses

What Happens: The water pump bearings often wear early, the impeller (especially plastic versions) can degrade, and leaks can develop. This can lead to overheating or coolant loss.
Signs to Watch For: Knocking or whining noises from the pump, coolant smell, visible leaks, erratic temperature gauge behavior.
Preventive Fixes: Replace the water pump before it fails (many owners do this around ~30-40k miles). Use pumps with better materials if available. Also inspect and replace coolant hoses and the reservoir if cracked. Clean debris from front radiators to avoid external damage.

What Happens: Seals tend to degrade with age and heat, leading to oil leaking between the engine and transmission (rear main seal), from the valve cover, or past the spark plug tubes. If left unchecked, oil can contaminate ignition components, damage wiring, or create smell/fire risks.
Signs to Watch For: Oily buildup under the car, oil on spark plugs/coils, burning oil smell, smoke under hard load.
Preventive Fixes: At major services, replace sealing bits proactively. Ensure a clean replacement surface when reinstalling valve covers or rear seals. Use high-quality gaskets/lubricants. If you spot oil on plugs, swap either seal right away.

What Happens: The AOS helps keep oil vapor from getting into the intake. When it fails, oil can be sucked into the intake manifold, which causes oil burning, misfires, and can accelerate rear main seal leaks.
Signs to Watch For: White/blue smoke on acceleration/startup, oil smell or residue in intake, check engine light for fuel trim faults, O₂ sensor issues.
Preventive Fixes: Replace or refurbish the AOS, especially if you track the car or drive spiritedly. Inspect the intake side and keep it clean. Use upgraded or heavier duty units if available.

What Happens: Some owners report sagging headliners, fading or loose interior trim, sunroof leaks (if applicable), and worn materials especially in hotter/humid climates.
Signs to Watch For: Headliner fabric sag, moisture or water stains, creaks/rattles while driving, poor seal on sunroof.
Preventive Fixes: Keep the car garaged or shaded to reduce heat damage. Address leaks immediately. Re-glue or replace trim early before damage becomes worse. Replace sunroof seals and check drainage.

What Happens: Gasoline Particulate Filters or related sensors can fail, become clogged, or cause engine control system warnings. These parts are expensive.
Signs to Watch For: Warning lights, driveability issues, increased fuel consumption, sometimes a “limp mode” or restricted performance.
Preventive Fixes: Keep the exhaust system healthy. Avoid frequent short trips (where regeneration doesn’t occur). Follow proper maintenance for sensors upstream (O₂, MAF etc.). If possible, use higher-grade fuels, ensure software is up to date.

What Happens: Inner CV boots or boots in half-shafts sometimes deteriorate or clamp loosen and leak grease. Transmission/shifter cables (in manuals) can stretch or wear, leading to sloppy shifts.
Signs to Watch For: Grease splatter around wheel wells, clicking or popping in drivetrain, gear shift that feels vague or doesn’t snap cleanly.
Preventive Fixes: Check boots regularly; replace if cracked. Inspect shifter linkage/cables along with bushings; replace worn components. Keep transmission fluid fresh, and ensure proper lubrication.

What Happens: Sensors (temperature, MAF, etc.), condensation/leaks on sensors, climate-control quirks, fan relays sticking, sometimes phantom warning lights from vacuum leaks.
Signs to Watch For: Random check engine lights, climate system not blowing correctly, fan running constantly, odd readings.
Preventive Fixes: Use quality replacement sensors; ensure proper routing & sealing of wiring harnesses; keep vacuum lines intact and replaced if hardened; update ECU software if Porsche has issued fixes.

What Happens: The exhaust / particle filter / catalytic converter assemblies are under high thermal stress. Heat can degrade sensors, gaskets, cause leaks. The components are costly.
Signs to Watch For: Burning smells under car, exhaust leaks, rattles from exhaust hardware, sensor warning lights.
Preventive Fixes: Inspect exhaust heatshielding; ensure mounting hardware is tight. Consider aftermarket upgraded components if you modify the exhaust or push the car hard. Regularly check underbody for damage or rust.

Pre-purchase checklist: If buying used, check water-pump history, oil leaks, condition of AOS, interior fit, sensor warnings, and whether the car has had shorter life use (track, frequent short drives).
Maintenance priority: Regular oil changes, coolant flushes, gasket/seal inspections, sensor checks, filter replacements.
Use a specialist where possible: Porsche-knowledgeable shops tend to catch issues like oil leaks or AOS failure earlier. OEM parts and proper labor matter—cheaper shortcuts often cost more over time.
Drive smartly: Warm the car up properly, avoid consistently low or high heat abuse (if possible). Give exhaust/trickle regeneration conditions chances to complete.