2020 MG ZS 1.0L Petrol · LG20 AAZ

The most recent MOT test on 22 June 2026 resulted in a pass, but only after a prior failure on the same date for an exhaust carbon monoxide exceedance following the second fast idle test, indicating that emissions compliance has become a recurring concern for this vehicle. Two prior annual tests, in June 2024 and June 2025, returned clean passes with no advisories, though the 2024 examination initially recorded a failure for a nearside front road wheel fixing being missing alongside an exhaust lambda sensor reading outside specified limits. Taken together, the trend is one of late-onset deterioration rather than steady decline, with the rear brake and tyre advisories representing the first signs of mechanical wear now appearing at the six year mark. The combination of an emissions failure and emerging rear axle component wear suggests the maintenance profile is shifting from clean to attention-required, and a buyer should treat the current pass as conditional rather than wholly reassuring. With 25,851 miles recorded over six years, annual usage averages around 4,300 miles, which is notably low and consistent with predominantly short urban trips, light weekend use, or extended periods of standing between journeys. Low annual mileage of this nature generally preserves major drivetrain components but accelerates certain age-related degradation, particularly in components that suffer from underuse rather than wear, such as brake discs corroding on the friction surface, brake calipers seizing, exhaust systems deteriorating internally from condensation cycles, and 12V battery sulphation from shallow charge states. The fact that an emissions failure has now manifested twice in close succession, despite such modest mileage, is consistent with a vehicle that has spent considerable time on short journeys or standing idle, allowing catalytic converter efficiency to decline and exhaust gas composition to drift outside limits. In terms of specific defect history, the rear brake disc advisory noted pitting and scoring not yet considered seriously weakened, but this condition will progress steadily and on a test drive the buyer should listen for a grinding or metallic scraping noise on light application, feel for any rear brake shudder through the pedal under firm stopping, and verify that the handbrake holds firmly without pulling to one side, as the rear calipers on low-mileage vehicles frequently bind from corrosion on the slider pins. Both rear tyres were flagged at the legal limit and perished at 3mm of tread, which is a critical replacement item before any purchase and indicates dry rot cracking in the sidewall rubber; perished tyres of this age can fail suddenly under load even if tread depth appears superficially adequate, and a close visual inspection of the sidewalls for circumferential cracking is essential. The recurring exhaust emissions failures are particularly noteworthy and warrant a pre-purchase diagnostic check of the lambda sensor data stream and catalytic converter efficiency, as persistent breaches of the post-fast-idle CO threshold often point to a failing oxygen sensor, contaminated engine oil, an ageing catalytic converter, or an air leak upstream of the lambda probe that distorts the air-fuel ratio. Beyond the recorded items, a six year old vehicle with low mileage also demands attention to several time-served components irrespective of test results. The 12V battery should be load tested, as short trip operation and prolonged standing typically shorten battery life well before mileage-related degradation would otherwise occur. Brake fluid should be replaced on a calendar basis rather than mileage, and given the age a fluid change is due if not already performed. Coolant, transmission fluid, and spark plugs on the naturally aspirated petrol unit should also be verified against the service schedule, and evidence of annual servicing with genuine MG parts sought in the service book. Underneath the vehicle, the buyer should jack the car or use a ramp to inspect the front subframe, brake lines, fuel lines, and exhaust hangers for standing corrosion from road salt exposure, and check the rear suspension coil springs and bushes for the brittle cracking common to low-use vehicles. Finally, a careful road test listening for any suspension clonks over speed humps and verifying that the steering remains centred will help confirm that the underlying mechanical condition supports the clean MOT picture before the next annual test cycle.