Peugeot 308 T9 1.6 THP

The EP6 Prince engine uses a timing chain that is known to stretch prematurely, particularly on early variants. The hydraulic chain tensioner can lose pressure overnight, resulting in a distinctive rattle on cold start that disappears once oil pressure builds. This typically develops between 80,000 and 120,000 km. If ignored, the chain can skip a tooth, causing valve timing misalignment and potentially catastrophic engine damage. PSA and BMW updated the chain design around 2012-2013, using stronger materials and redesigned guides (white PVC guides replaced the original brown ones). Replacement involves the full timing chain kit including chain, tensioner, guides, and sprockets. At an independent garage in Germany, expect €900-1,300 (parts around €300-500, labor 6-8 hours). At a Peugeot dealer, costs can reach €1,500-1,800.

The high-pressure fuel pump on THP engines is a well-known weak point. Failures typically occur between 80,000 and 130,000 km, manifesting as hesitation at low rpm, intermittent misfires, and eventually limp mode with fault code P0087 (fuel rail pressure too low). The pump is driven by a cam lobe and wears internally over time. BMW covers a similar component for 8 years under warranty on their N14/N18 variants, but Peugeot does not offer equivalent coverage. An aftermarket or remanufactured pump costs around €250-350, while the genuine Peugeot part is €500-650. Total replacement cost including labor is €600-800 at a specialist or €900-1,200 at a Peugeot dealer.

As a direct injection engine, fuel bypasses the intake valves entirely. Oil vapors from the PCV system and exhaust gases from the EGR system deposit carbon on the back of the valves. This gradually restricts airflow, causing rough idling, reduced power, and increased fuel consumption. The engine can lose up to 20% of its original power according to specialist reports. Symptoms typically appear between 50,000 and 80,000 km. Walnut blasting is the standard cleaning method, costing €300-500 at an independent specialist. At a Peugeot dealer, quotes can exceed €800. Regular highway driving at higher rpm helps slow the buildup, while predominantly urban driving accelerates it. Cleaning should be considered every 50,000-60,000 km as preventive maintenance.

The intake camshaft variable valve timing system relies on an oil control solenoid that regulates pressure to the cam phaser mechanism. Over time, oil residues contaminate the solenoid, causing it to stick or deliver incorrect pressure. Symptoms include lean/rich running, misfires, erratic fuel trim values, and engine knock at low rpm. The solenoid itself is relatively inexpensive (€80-150) and can be cleaned as a temporary fix. However, if the camshaft oil rings or the cam phaser mechanism itself are worn, replacement costs increase significantly to €800-1,200 including labor. This issue is more common on cars that have been driven with extended oil change intervals or incorrect oil viscosity.

Ignition coils on the 1.6 THP have a notably high failure rate compared to other engines in this class. When a coil fails, the engine runs on three cylinders, causing noticeable juddering, power loss, and the engine fault warning light. A single coil costs €30-60 for aftermarket or €60-90 for genuine Peugeot parts. Most specialists recommend replacing all four coils at once (€120-250 for parts) as a preventive measure once one fails. Total cost including labor is €150-400 depending on whether individual or all coils are replaced. Failures can occur from 60,000 km onward. Using NGK Platinum or Iridium spark plugs with 0.8mm gap and replacing them every 30,000 km helps extend coil life.

The turbocharger on THP engines can develop hairline cracks in the housing, particularly the compressor outlet and turbine housing, typically appearing after 60,000-80,000 km. This causes oil leaks visible around the turbo area and may progress to blue or black smoke from the exhaust. Additionally, turbo wastegate actuator issues can cause boost control problems and limp mode. A reconditioned turbo with fitting costs €800-1,200 at an independent specialist. A new genuine turbo with installation runs €1,800-2,500 at a Peugeot dealer. If only the wastegate actuator is faulty, standalone replacement is possible for €300-500.

The EP6 uses an electronically controlled thermostat that regulates engine temperature more precisely than a conventional wax-element thermostat. However, the electronic control degrades over time, typically after 70,000 km, causing extended warm-up times and poor cabin heating. In some cases, the thermostat can stick closed, causing overheating which can lead to head gasket damage. The plastic coolant pipe running from the thermostat to the water pump is also prone to cracking. Replacement of the thermostat housing and associated piping costs €400-600 at an independent garage. If the water pump needs replacing simultaneously, total costs reach €600-900.

The 308 T9 i-Cockpit infotainment system is known for touchscreen glitches. Common symptoms include the screen going blank and restarting every 5-10 minutes, unresponsive touch inputs, and temperature-related failures where the screen works in cool weather but fails in summer heat. Software updates from the dealer have resolved the issue for some owners, but in persistent cases the head unit needs replacing. A new head unit from Peugeot costs €500-800 fitted. Third-party refurbished units are available for €300-400. This issue affects both pre- and post-facelift models.