Bob explains the most common reasons diesel cars fail their MOT in the UK — DPF blockages, emissions, EGR faults, injectors and more — with honest tips to pass first time.
Common Diesel MOT Failure Reasons in the UK – And How to Pass First Time Hello, Bob here from Bob's Mechanical Repairs in Birnam. After 32 years on the tools, I've seen just about every reason a diesel car can fail its MOT — and most of them are completely avoidable with a bit of know-how. If you dr
ive a diesel in the UK, this guide is for you. Modern diesels are clever bits of kit, but they're also fussy. The MOT emissions standards got noticeably tougher in 2018, and a lot of perfectly healthy-feeling diesels now fail simply because the owner doesn't know what the test actually checks. Let's
fix that. 1. DPF (Diesel Particulate Filter) faults — the number one diesel MOT failure The DPF is the biggest single reason diesels fail an MOT in the UK. Since May 2018, an MOT tester must: - Visually check the DPF is fitted - Fail the car if there's any sign the DPF has been removed, cut open, o
r tampered with - Fail the car if there's visible smoke of any colour from the exhaust - Fail the car if the MIL (engine warning light) shows a DPF fault A blocked DPF often shows up as poor performance, limp mode, or that orange exhaust warning light on the dash. Lots of short, low-speed journeys a
Bob's Mechanical Repairs — independent family-run garage in Birnam, Dunkeld, Perthshire. Call 01350 727 276 or email [email protected].