2017 Mercedes-Benz Citan 1.5L Diesel · NG66 ACU

A recurring corrosion theme dominates the roadworthiness profile of this 2017 Mercedes-Benz Citan, with structural advisories appearing at every recent test and culminating in a failed attempt in February 2026 that was rectified the following day. The 2026-02-02 failure was an electrical compliance issue, a defective rear number plate lamp, rather than a mechanical defect, which means the advisories logged on that date should still be read as the genuine mechanical condition of the vehicle at the time. The fact that both front shock absorbers are showing external casing corrosion and the rear axle and suspension components are described as corroded but not seriously weakened points to ongoing chassis degradation, a common finding on Citan vans of this generation given their commercial-duty background. The 2024 test additionally flagged corroded rear brake pipes, and although these were recorded as being covered in grease or other material rather than advanced corrosion, brake pipework is a safety-critical item that warrants close physical inspection. With 82,401 miles recorded over approximately nine years, annual mileage averages around 9,156 miles, which sits within the expected range for a small commercial-derived van of this age. There are no significant gaps in the testing record, with annual tests consistently filed from 2023 onwards, indicating the vehicle has remained in regular use rather than being laid up. The smooth brake pedal advisory from 2023 has not reappeared in subsequent records, suggesting that wear item was either addressed or did not progress to a further defect. The cumulative mileage is sufficient that consumables such as brake pads, discs, tyres, and the dual-mass flywheel if a manual diesel should already have been replaced at least once, and the recorded corrosion findings are consistent with a vehicle that has seen real-world mileage in mixed conditions rather than garage-kept light use. For a prospective buyer, the priority area is the suspension and underbody condition flagged across the 2024 and 2026 tests. The rear axle and suspension components should be raised on a ramp for a thorough inspection, paying particular attention to the coil springs, trailing arms, anti-roll bar links, and mounting points for any advanced corrosion beyond the surface level described in the advisories. The front shock absorber casings should be examined for any bubbling, flaking, or perforation that could indicate the corrosion is migrating to the internal piston rod sealing area, and any knocking from the front suspension over uneven surfaces on a test drive would suggest the shock absorbers are beginning to fail mechanically. Listen for clonking or rattling from the rear over speed humps and rough tarmac, which would suggest the corroded rear components have worsened since the advisory was issued. The brake system requires equally careful scrutiny given the 2024 pipe corrosion advisories and the general age of the vehicle. Inspect the full length of the brake pipes, particularly along the underbody and rear axle where road salt and moisture accumulate, looking for any pitting, rust blooms, or flaking that would indicate the protective coating has deteriorated beyond what grease can mask. On a road test, the brake pedal should feel firm and progressive; any sponginess, excessive travel, or a brake warning light would warrant immediate investigation of the hydraulic system. The failed rear number plate lamp is a minor compliance fix, but it is worth checking all exterior lighting, including the obligatory side repeaters and the often-overlooked load area illumination if the vehicle remains in van configuration. Finally, with diesel Citan models being prone to injector and EGR issues at this mileage, a thorough scan for fault codes and a cold-start observation are recommended to confirm the engine management system is functioning correctly.