Why does emissions test unable to be completed fail an MOT?

Emissions test unable to be completed. Most commonly flagged on the Perodua Kelisa. The DVSA's MOT standards require this item to meet minimum safety thresholds — when it falls short, the tester logs it as a Major or Dangerous defect and the car fails outright.

How much does it cost to fix emissions test unable to be completed?

Costs vary depending on the vehicle, region, and severity. Use our MOT cost estimator for typical UK garage rates across the most common failure items.

Emissions test unable to be completed — MOT failure (140 cars, 2023)

Models most at risk.

Ranked by rate, not raw volume. A Fiesta shows every failure a lot because there are a lot of Fiestas. Rate = share of that model's own MOTs.

Cost orientation

Hard to predict in isolation — depends what's actually worn.

This defect doesn't map to a clean retail-part swap; ranges vary too widely without seeing the car. Use the estimator to bracket the all-in cost across the items most likely to surface alongside it.

Open estimator

Frequently asked.

Why does emissions test unable to be completed fail an MOT?: Emissions test unable to be completed. Most commonly flagged on the Perodua Kelisa. The DVSA's MOT standards require this item to meet minimum safety thresholds — when it falls short, the tester logs it as a Major or Dangerous defect and the car fails outright.
How much does it cost to fix emissions test unable to be completed?: Costs vary depending on the vehicle, region, and severity. Use our MOT cost estimator for typical UK garage rates across the most common failure items.