Peugeot 5008 1.6 THP Mk1

The EP6 engine's timing chain is its most critical weakness. Pre-November 2011 engines used a tensioner with a soft seal that allowed oil pressure to bleed off overnight, causing the chain to go slack. This produces a distinctive rattle on cold start lasting up to 30 seconds. If ignored, the chain can skip teeth and cause catastrophic valve-to-piston contact. From late 2011, PSA introduced an updated tensioner that reduced but did not eliminate the issue. The plastic chain guides can also disintegrate, contaminating the oil system. Replacement involves chain, guides, tensioner, and VVT sprockets. An independent specialist charges around €800-1,200, while Peugeot dealers quote €1,500-2,000. The engine specialist community recommends treating replacement as a when-not-if item by 80,000-100,000 km. Frequent oil changes with quality 5W-30 at 10,000 km intervals are the single most effective preventive measure. The heavier 5008 body does not accelerate chain wear compared to lighter cars with the same engine, as chain stress is RPM-related rather than load-related.

The HPFP is a well-documented weak point across all Prince THP engines. The pump contains a hydraulic diaphragm with a small oil reservoir that depletes over time as internal sludge accumulates. Symptoms include intermittent stuttering under load, difficulty with hot restarts, rough idle, and fault code P0087. Typically fails between 60,000-120,000 km. Peugeot offered goodwill contributions for cars under 6 years old and 60,000 miles, and BMW covered the equivalent part for 8 years on the Mini Cooper S. A refurbished pump costs €100-200 from a specialist, while a new genuine pump runs €400-600. Total repair including labor is €250-500 at an independent garage or €700-1,000 at a Peugeot dealer. Short-trip urban driving accelerates pump degradation. The problem is often misdiagnosed as ignition coil failure since symptoms overlap.

As with all direct-injection engines, fuel does not wash over the intake valves, so carbon deposits from PCV oil vapors accumulate on the valve stems and ports. The THP engine is particularly susceptible due to its PCV routing and tendency toward oil consumption. Symptoms develop gradually: rough idle, misfires, reduced throttle response, and measurable power loss of 15-20%. The problem cannot be detected by standard diagnostics because it does not trigger error codes. Typically becomes noticeable between 50,000-80,000 km. Walnut blasting is the most effective cleaning method, costing €350-600 at a specialist. The buildup will recur every 40,000-60,000 km. Regular spirited driving at higher RPMs helps slow the accumulation, while predominantly urban short-trip driving accelerates it significantly. Some owners fit oil catch cans to reduce oil vapor reaching the intake, at a cost of around €100-150.

The EP6 engine uses an electronically controlled plastic thermostat housing that becomes brittle over time from repeated heat cycling. Micro-cracks develop and allow coolant to weep, typically at the bypass pipe connection. Failure can cause the engine to run too cool (poor cabin heating) or too hot (overheating risk). PSA released a revised thermostat housing part. Replacement costs €250-400 at an independent garage or €400-600 at a Peugeot dealer. If coolant loss goes undetected and the engine overheats, head gasket damage can follow with repair bills exceeding €2,000. Typically appears between 70,000-120,000 km. Regular coolant level checks are essential.

The KKK K03 turbocharger has two failure modes. First, the factory oil feed pipe uses a fragile O-ring that degrades from repeated heat cycles, causing oil to leak onto the turbo and exhaust manifold. This creates a burning oil smell and visible smoke. The upgraded braided stainless steel oil feed pipe costs around €100-150 and is recommended as preventive maintenance. Second, the turbine housing material can develop hairline cracks after 60,000-80,000 km of heat cycling, particularly on cars driven hard and immediately switched off without a cool-down period. If the turbo itself fails, a remanufactured unit costs €500-800 while a new genuine turbo runs €1,000-1,500. Total replacement including labor is €800-2,000. Always replace the oil feed pipe when fitting a new turbo.

The EP6 engine's crankcase ventilation system uses a rubber diaphragm integrated into the valve cover. When this membrane tears, it disrupts crankcase pressure regulation, pulling excessive oil vapor into the intake and increasing oil consumption significantly. Symptoms include oil consumption above 1 liter per 3,000 km, blue smoke on startup, and rough idle. Neither Peugeot, Citroen, nor Mini sell the diaphragm as a separate part; the official fix is a complete valve cover replacement at around €300-400 including labor. Third-party diaphragm kits are available for around €15-25, making the repair €100-150 at an independent garage that is willing to fit the aftermarket part. The diaphragm typically fails between 60,000-100,000 km.

The 1.6 THP generates considerable heat in a compact engine bay, and the ignition coils take significant thermal stress. Moisture can also collect around the coil wells and cause corrosion. A failed coil causes misfires on the affected cylinder, producing juddering and power loss. This is frequently misdiagnosed as HPFP failure since symptoms overlap. A single coil costs €30-60 aftermarket or €60-90 genuine. Replacing all four coils with spark plugs costs €150-400 depending on parts choice. The specialist community recommends replacing all four coils and plugs every 30,000-40,000 km as preventive maintenance. Using 98 octane fuel also helps keep combustion chambers cleaner.

The 5008 Mk1 uses an electronic parking brake that is more complex than a traditional handbrake. Common failures include the dashboard switch, the electric motors inside the rear brake calipers, and wheel speed sensor issues that trigger system errors. A faulty switch is the cheapest fix at around €50-150. A defective caliper motor typically costs around €300-500 to replace. Diagnosis requires Peugeot-specific software (Diagbox/Lexia) as generic OBD readers often cannot communicate with the EPB system. This issue also applies to the diesel variant and is not THP-specific.