1.5.a
Additional braking device (retarder) performance · Additional braking device (retarder) performance
Major · Rectify before re-test.
Control for electronic retarder does not allow gradual variation in effort
DVSA manual phrasing — written for testers, kept verbatim.
May affect the vehicle's safety, put other road users at risk, or have an impact on the environment. The vehicle has failed the MOT.
Additional braking device (retarder) performance
- Section 1
- Brakes
- 1.5
- Additional braking device (retarder) performance
- 1.5
- Additional braking device (retarder) performance
- 1.5.a
- this defect
Rectify before re-test.
Always confirm with a qualified MOT tester or vehicle technician for your specific vehicle. A re-test must address the defect category identified above.
Related codes in this subject
motfailcode.uk maps DVSA MOT defect codes to plain-English meanings. Defect severity classifications follow the DVSA MOT Inspection Manual current as of 12 May 2026. Codes and severities are updated annually (typically May). Always confirm with a qualified MOT tester or vehicle technician for your specific vehicle. This site is not affiliated with DVSA or HM Government.
See our methodology for how we extract and verify each code, and sources for the full citation manifest.