Misfires and sluggish acceleration due to altered valve timing.
This engine is known to consume oil at an alarming rate, often due to failing valve stem seals, worn piston rings, or a faulty PCV system built into the valve cover. If the engine oil drops too low, or if poor-quality oil degrades, the turbocharger bearings are starved of lubrication. Furthermore, the oil feed lines to the turbocharger frequently clog with sludged oil. Symptoms:
The thermostat housing is prone to leaking or cracking, and the electric water pumps are known for early wear.
The Prince engine family, co-developed by BMW and PSA Peugeot Citroën, was a marvel of late-2000s engineering—on paper. Designed to replace the outdated Tritec and TU engines, the Prince series promised a sweet spot of efficiency, power, and low emissions. Among its variants, the (often referred to as the THP150 or Prince 1.6 THP) became one of the most widespread, powering vehicles like the Mini Cooper S (R56) , Peugeot 207 GTi , Citroën DS3 Racing , and BMW 116i/118i (E87) . ep6dt engine problems
The cooling system is mostly plastic, which becomes brittle over time, leading to leaks.
Replace the cracked plastic thermostat housing with a reinforced aftermarket unit. Check for recalls regarding the auxiliary turbo water pump, as many were replaced under manufacturer campaigns. Preventative Maintenance Summary
The plastic thermostat housing (water neck) frequently cracks, develops leaks, or suffers from internal sensor failures. Furthermore, the electronic water pump used for auxiliary turbo cooling can fail or leak. Visible puddles of coolant underneath the vehicle. Misfires and sluggish acceleration due to altered valve
Because the EP6DT utilizes Gasoline Direct Injection (GDI), it is highly susceptible to carbon accumulation. The Problem
Because the EP6DT utilizes Gasoline Direct Injection (GDI), fuel is sprayed directly into the combustion chamber rather than over the back of the intake valves.
or metallic banging sound during cold starts that often disappears once the engine warms up. Consequences: Furthermore, the oil feed lines to the turbocharger
Owners frequently report faulty HPFPs that fail to provide enough pressure at idle, resulting in stuttering or stalling.
| Problem | Repair Solution | Preventive Maintenance | | :--- | :--- | :--- | | Timing chain | Replace chain, tensioner, guides, and VANOS sprockets (use updated parts). | Replace tensioner every 50k miles as precaution. | | HPFP | Replace HPFP and flush low-pressure fuel system. | Use Top Tier 93 octane fuel; change fuel filter regularly. | | Carbon buildup | Walnut blast intake valves every 40k-60k miles. | Install oil catch can; use low-SAPS oil; perform Italian tune-ups. | | Turbo oil feed | Replace banjo bolt with revised, larger-filter version. | Change oil every 5k miles with full synthetic 5W-30/5W-40. |
The tiny oil feed line to the turbo cokes up due to heat. When blocked, the turbo starves of oil and . Prevention: Replace the oil feed line with the updated, larger-diameter version. Use high-quality synthetic oil changed every 5k miles, not 10k.
Because the EP6DT utilizes Gasoline Direct Injection (GDI), it is highly susceptible to carbon accumulation.