Before you buy a used Renault Mégane (IV).

Look out for: Metallic chain rattle, especially when cold or at idle; engine light with a crankshaft–camshaft correlation code; in serious cases the chain jumps and damages the valves.

Ask them to check: With any chain noise or a P0016 code, diagnose straight away: measure the stretch and check the tensioner and guides before the timing jumps. Shorten oil-change intervals.

Look out for: Particulate-filter or emissions warning, limp mode with loss of power and frequent regenerations.

Ask them to check: Read the soot load with a diagnostic tool, run a forced regeneration at the garage and check the differential-pressure sensors and EGR. Make long road trips now and then.

Look out for: After a visit to the dealer, flat spots when accelerating and judder at steady speeds; sometimes higher diesel consumption. On the Mégane IV and Kadjar the engine may start and then stall.

Ask them to check: Ask a Renault or Dacia dealer for the new injection ECU reprogramming for these symptoms (Dacia has offered it since May 2024 and Renault since January 2025). It is not a recall with a letter: you have to ask for it. First have them rule out other causes (particulate filter, boost pressure sensor).

Look out for: Uneven idle, jerks when accelerating, lack of power or the engine going into limp mode, sometimes with the engine warning light on.

Ask them to check: At the workshop: read the codes with diagnostic equipment (EOBD P0400 to P0404 or P0172; Renault DF077, DF084 or DF241), test the valve electrically and its opening with the engine warm, and find where the oil comes from (breather, turbo, level). Pierburg advises against cleaning it, as it can be damaged: it is replaced if faulty, and an engine ECU update sometimes solves it.

Look out for: Chain noise on start-up on the 1.2 TCe (H5F); an EDC gearbox that overheats or jerks when pulling away (especially GT TCe 205); drop links; at the roadworthiness test, suspension and lights.

Ask them to check: Check the campaigns by VIN; change the EDC oil every 50,000–60,000 km; listen to the 1.2 TCe chain.

Look out for: “Stop” warning with the message “electrical fault, danger”, loss of drive and the car stranded.

Ask them to check: Ask Renault by VIN whether the reprogramming was done; with the warning, stop somewhere safe.

Look out for: The message “surchauffe moteur électrique” (electric motor overheating, Renault internal code 0A9098) or loss of drive when pulling away that means the car has to be towed (code 16D861).

Ask them to check: Check by VIN with Renault or Dacia whether the car is in campaign 0ET1 / 0EWW and whether it has been done. With the overheating warning, the garage removes the electric motor temperature sensor and looks for oil; if there is any, it replaces the O-ring, cleans the electric motor and may update the HEVC and HECM computers. If the car no longer drives, the whole gearbox is replaced.

Look out for: A shrill noise when the car tries to start the petrol engine; the instrument panel may show “Panne moteur électrique” (electric motor fault) or “Risque de casse moteur” (risk of engine damage), and the petrol engine may fail to start.

Ask them to check: Check the build date and ask Renault for a gearbox diagnosis quoting operation OTS 0EJQ. It is not a recall: Renault does not write to owners, so you have to go to the garage and describe the noise.

Look out for: Hard to start or will not start, stalls, loses power or jerks; sometimes air bubbles show in the clear fuel pipe.

Ask them to check: At the workshop, in this order: look for air and leaks in the low-pressure circuit and prime it; check the fuel filter bowl for metal swarf (if there is any, the whole injection system is replaced); measure the rail pressure, the IMV regulator's resistance (4.8–5.8 Ω) and each injector's return flow (25 ml at most in the test). A new injector's code must be written into the ECU.