2012 Mercedes-Benz B-Class 1.8L Diesel · PN12 AEW

The most recent MOT history for this 2012 Mercedes-Benz B-Class reveals a concerning pattern of repeated failures despite no recorded defects on either attempt in November 2025. The vehicle passed cleanly in November 2022 and November 2024, yet failed twice in quick succession just before the latest pass in November 2025—suggesting an underlying issue that evaded detection during the final inspection. The lack of specific fault codes in the failed tests implies either a non-mechanical administrative error or a critical component that only manifested intermittently, such as a failing emissions system or electrical fault tied to the engine management or exhaust. The November 2025 pass, just two days after the failure, further raises suspicion of a rushed or incomplete inspection, particularly given the identical mileage on both attempts. The recorded mileage progression of approximately 8,750 miles per year aligns with typical usage for a vehicle of this age, though the abrupt accumulation of 10,273 miles between November 2024 and November 2025 stands out. This spike—nearly double the average annual mileage—could indicate either intensive use or a period of under-maintenance, as higher mileage accelerates wear on suspension bushes, coil springs, and brake components. The absence of any MOT tests between November 2022 and November 2024 (a gap of 22 months) is also notable, as it suggests either prolonged off-road storage or a period where the vehicle was not subject to regular scrutiny. The most recent pass in November 2025, just 122,527 miles from the last test, means the vehicle has already exceeded the 12-month interval for an MOT, leaving it technically overdue by several months as of July 2026. Given the repeated failures and the lack of specific fault details, a buyer should prioritise an independent inspection of the exhaust system, particularly the catalytic converter and downstream oxygen sensors, as these are common causes of intermittent MOT failures. The suspension should be thoroughly checked for worn or leaking bushes, as well as coil spring integrity—especially in the rear, where binding calipers or uneven wear often goes unnoticed. Brake discs and pads should be examined for lateral corrosion or uneven thickness, while the anti-lock braking system (ABS) and electronic stability control (ESC) modules warrant testing for error codes, as these are frequently tied to emissions-related failures. Structural corrosion in the wheel arches, sills, and subframe should also be assessed, as this is a critical but often overlooked risk in vehicles of this age. The repeated failures suggest the previous owner may have overlooked minor issues, so a detailed service history beyond the MOT record would provide further clarity.