Common Problems with the
2018 Peugeot 508 (Gen 2)

On 1.5 BlueHDi (DV5) and 2.0 BlueHDi (DW10) diesel engines, the integrated AdBlue SCR tank system is a frequent failure point. The internal dosing pump, heating element, or tank pressure sensors suffer electronic faults or urea crystallization, or the tank deforms. This triggers an amber UREA warning, emissions engine fault light, and an unyielding countdown preventing engine restart once the countdown reaches zero. Rectification typically demands replacing the entire sealed plastic tank assembly, as individual pump and sensor modules cannot be serviced separately.

The 1.5-litre BlueHDi (DV5) diesel engine built prior to early 2023 utilizes a 7mm auxiliary timing chain linking the twin overhead camshafts, independent of the external timing belt. Due to carbon buildup and high stress, the 7mm chain prematurely stretches, slaps against the rocker housing, and can snap without warning. Chain failure throws camshaft timing out of phase, causing valves to collide with pistons and requiring cylinder head rebuilding or full engine replacement. Peugeot later engineered an upgraded 8mm chain kit with modified camshafts under safety campaigns.

On 1.2 PureTech petrol models, the engine uses a wet timing belt running directly submerged in hot engine oil. Using incorrect oil formulations, short urban trip fuel dilution, or age causes the belt's rubber compound to crack and shed fibrous debris. This dislodged debris collects in the oil sump and clogs the oil pump pickup strainer screen, causing oil starvation, brake vacuum pump loss of servo assistance, and eventual bottom-end engine seizure. Stellantis lowered the belt replacement interval and issued technical service actions.

The fastback coupe styling of the 508 Gen 2 uses frameless side glass that must automatically drop slightly when the door handle is pulled and rise into the weatherstrip upon closing. In freezing UK winter conditions, the glass frequently freezes solid against the rubber seals, causing the anti-pinch mechanism to trigger or damaging the electric window regulator cables and plastic clips. Over time, worn or dry window seals also lead to wind buffeting, high-speed cabin whistle, and damp ingress along the door cards.

The i-Cockpit system on the 508 combines a 12.3-inch configurable digital instrument cluster with an 8-inch or 10-inch central touchscreen running NAC infotainment firmware. Software stability issues, slow telematics processors, and loose rear harness grounds frequently manifest as frozen displays, complete touchscreen blackouts, lost Bluetooth or smartphone mirroring connectivity, and delayed heater controls. In most instances dealer ECU and telematics firmware reflashes cure the glitch, though hardware screen replacement is occasionally required.