Peugeot 508 1.5 BlueHDi Mk2

The 1.5 BlueHDi DV5RC engine produced between October 2017 and January 2023 uses a 7mm timing chain that wears prematurely. Soot-laden oil accelerates chain and tensioner degradation. Early warning signs include a metallic rattling for 1-30 seconds on cold start. If the chain snaps, pistons and valves collide, typically requiring a complete engine replacement at 4,000-6,000 euros. A second batch of supposedly upgraded chains from late 2019 also proved insufficient, triggering a formal recall across over one million Stellantis vehicles. Stellantis extended coverage to 10 years / 150,000 miles from first registration (announced mid-2025), covering 100% of parts and labour. Conditions: maintenance must follow manufacturer intervals using approved oil (Total Quartz INEO RCP 5W30), and proof of the last three services is required. Preventive chain replacement with the upgraded 8mm chain costs 2,000-3,000 euros at an independent specialist. Retroactive reimbursement is available for repairs paid between January 2023 and June 2025 via stellantis-support.com. This is the single most important check before buying any 1.5 BlueHDi.

The second most common issue on the 1.5 BlueHDi. The AdBlue injector blocks from urea crystallisation, while the pump (built into the AdBlue tank) fails when its circuit board is contaminated by AdBlue fluid leaking into the sealed electronics compartment. Early 2018-2019 builds are most affected. Symptoms include an AdBlue warning light despite adequate fluid level, and eventually a countdown message threatening engine lockout. A software reset fixes some false alarms at 100-150 euros. NOx sensor replacement costs 400-700 euros. Full AdBlue tank and pump replacement runs 1,500-2,500 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 approximately 10 litres at a time from a reputable source.

The DPF requires periodic high-temperature regeneration to burn off accumulated soot. This only happens during sustained driving at motorway speeds (60+ km/h for 15+ minutes). Cars used predominantly for short urban trips saturate the filter. Some owners report regeneration cycles as frequent as every 40-70 km instead of the normal 150-500 km interval, indicating the system is struggling. Professional chemical cleaning costs 250-400 euros. If the filter is beyond cleaning, replacement runs 900-1,500 euros. A key warning sign before purchase: if the engine oil level is well above the maximum mark and smells of diesel, this indicates chronic regeneration failure from fuel dilution. Cars with regular motorway use rarely have this problem.

The EGR valve recirculates exhaust gases and accumulates carbon deposits, particularly on gently driven cars and those used for urban journeys. Symptoms include rough idle, flat spots during light acceleration, and increased fuel consumption. On the 1.5 BlueHDi, the EGR comes as a complete module with the heat exchanger built in, meaning it cannot be disassembled for cleaning without risk. Professional cleaning costs 200-400 euros and can restore function for 6-12 months. Full EGR module replacement costs 400-700 euros at an independent workshop. Peugeot dealer pricing is higher at around 600-900 euros. Regular motorway driving helps reduce buildup.

The 508 Mk2 i-Cockpit system uses a large central touchscreen that controls climate, navigation, and vehicle settings. Owners report the screen freezing, going black after startup, or rebooting mid-drive. A soft reset by holding the phone button for 8-10 seconds often resolves temporary glitches. Software updates from Peugeot have addressed many of the recurring bugs, particularly on early 2018-2019 production cars. If software updates do not resolve the issue, a replacement head unit costs 300-500 euros. Used units from breakers cost 100-200 euros but require dealer coding. While frustrating, this does not affect vehicle drivability.

The 508 Mk2 electronics are sensitive to voltage drops from the 12V battery. A weakening battery (typically after 3-5 years) can trigger cascading fault codes including engine fault, gearbox fault, ESP, and spanner icons appearing and disappearing. Many owners have resolved these symptoms simply by replacing the battery at 80-150 euros fitted. Battery registration via Peugeot-compatible diagnostics is recommended to ensure the charging system adapts correctly. Turning off unnecessary standby features (ambient lighting, motion sensor alarm) when the car is parked for extended periods helps preserve battery life. Replace the 12V battery every 4-5 years as preventive maintenance.