Peugeot 508 2.0 BlueHDi Mk1

The 508 uses an additive-assisted DPF system (Eolys cerine fluid on pre-2014 models, integrated DPF on BlueHDi models). Short trips under 15-20 minutes prevent the exhaust from reaching regeneration temperature. Symptoms include the anti-pollution warning, engine warning light, and reduced power. A professional forced regeneration costs 150-250 euros. DPF chemical cleaning runs 300-500 euros. Full DPF replacement costs 800-1,500 euros depending on OEM or aftermarket parts. The Eolys additive tank (pre-2014 models) needs topping up approximately every 120,000 km at around 100-150 euros. Check the engine oil level before purchase: if well above the maximum mark and smelling of diesel, this indicates chronic regeneration failure from fuel dilution. Cars with regular motorway use rarely have this issue.

This issue only affects the 2014+ Euro 6 BlueHDi variants with SCR (selective catalytic reduction). The AdBlue injector crystallises from urea deposits, while the pump electronics (integrated into the AdBlue tank) can be contaminated by fluid ingress. NOx sensors give faulty readings after 80,000-100,000 km. Symptoms include an AdBlue warning light with a countdown message, even with a full AdBlue tank. Peugeot dealers reportedly average two AdBlue faults per day across their workshop bookings. Pressure sensor replacement costs 150-300 euros. A single NOx sensor runs 350-500 euros. Full AdBlue tank and pump replacement costs 800-2,000 euros because the pump cannot be purchased separately. Peugeot has offered goodwill contributions of up to 75% on well-serviced cars. Only refill AdBlue when the car prompts you, using branded fluid.

The 508 Mk1 has a complex rear suspension with an H-shaped subframe that uses four large rubber bushings to connect to the chassis. These bushings deteriorate from road salt, vibration, and age, typically starting around 60,000-80,000 km. Symptoms include clunking or knocking over bumps, vague rear-end handling, and uneven inner rear tyre wear. Each bushing costs approximately 70-150 euros for the part. Total repair including alignment runs 400-800 euros at an independent specialist, as the subframe must be partially lowered for access. This issue often needs addressing twice during a 10-year ownership period. Inspect the bushings visually for cracking and separation before purchase.

The electronic parking brake on the 508 Mk1 is a known weak point. Water can seep into the EPB unit via the emergency release cable access hole, corroding internal components. Symptoms include a 'Parking brake fault - have vehicle repaired' message, the brake failing to release on start-up, or intermittent engagement. Before expensive repairs, check the battery voltage (low voltage triggers false warnings) and the 20-amp EPB fuse, as many owners have resolved the issue by simply replacing a blown fuse at minimal cost. The EPB switch itself costs 50-100 euros. Caliper motor replacement runs approximately 300-500 euros per side. Full EPB module replacement costs 500-600 euros. Diagnosis requires Peugeot-specific software (Diagbox/Lexia), as generic OBD readers often cannot communicate with the EPB system.

The EGR valve on the DW10 engine accumulates carbon deposits from recirculated exhaust gases, particularly on gently driven cars and those used mainly for urban journeys. Mechanics report that while all EGR valves eventually foul, the 2.0 HDi is one of the more robust ones. Symptoms include rough idle, flat spots during light acceleration, and increased fuel consumption. Cleaning costs 150-250 euros and can restore normal operation for 6-12 months. A new EGR valve with fitting costs 300-600 euros at an independent workshop. Peugeot dealer pricing is higher at 500-800 euros. The valve is located at the rear of the engine, making access awkward and adding to labour time. Regular motorway driving and quality diesel help reduce buildup.

The 2.0 HDi produces up to 340-400 Nm of torque, which gradually fatigues the dual mass flywheel. Symptoms include metallic rattling at idle that changes when the clutch pedal is pressed, and juddering when moving off in first gear. Typical failure occurs between 130,000-180,000 km depending on driving style. The DMF should always be replaced together with the clutch assembly, as gearbox removal is required for access. Scheduled labour time is approximately 6 hours. An independent garage charges 800-1,200 euros for parts and labour using quality aftermarket components. A Peugeot dealer quotes 1,200-1,600 euros with OEM parts. Urban stop-start driving and riding the clutch accelerate wear significantly.

The variable-geometry turbocharger on the DW10 engine uses an electronic actuator to control vane position. Carbon deposits from the EGR system gradually restrict actuator movement, particularly on gently driven cars that rarely reach higher RPMs. Symptoms include intermittent limp mode, engine management warning lights, and noticeable power loss. If caught early, specialist actuator repair costs 200-400 euros. However, if the internal turbo vanes are also seized or the bearings are damaged from insufficient oil supply, a complete turbo replacement is needed at 1,200-2,000 euros fitted. The DW10 2.0 HDi turbo is more durable than the 1.6 HDi's, with failures typically not appearing before 150,000 km. Always replace the oil feed pipe when fitting a new turbo to prevent recurrence.

A well-documented issue on the 508 Mk1 where the central infotainment screen powers up briefly then goes black after a few minutes, or does not start at all. The radio and Bluetooth functions may continue working normally while the screen remains dark, making navigation and climate controls inaccessible. The root cause is typically a failing internal component in the head unit. Specialist electronics repair services offer head unit rebuilds for 200-300 euros. A new or refurbished replacement unit from Peugeot costs 400-600 euros including coding. Used units from breakers are available for 100-200 euros but require dealer coding to the vehicle. While annoying, this issue does not affect vehicle drivability.