Compression ignition: inoperative or indicates a malfunction
This one item accounted for 0.1% of every MOT test carried out in Great Britain, and it is among the commonest faults on 128 different model-and-year combinations. Here is where it clusters, and what it looks like on a car you are standing in front of.
How to spot it before you buy
Check the dash for a DPF or emissions warning and ask when it was last regenerated
A blocked DPF on a car used for short trips is a common, expensive fault (£300–1,500+).
The models it hits hardest
Ranked by how often the fault came up as a share of that model's own tests, not by raw count — a fault in 8% of a small model's tests says more about that model than one in 3% of the Fiesta's. A linked row has a page of its own.
| Model | Years | Share of its tests |
|---|---|---|
| Nissan Navara | 2010–2013 | 3.9% |
| Nissan Navara | 2014–2017 | 3.7% |
| SEAT Alhambra | 2010–2013 | 3.2% |
| Hyundai I800 | 2014–2017 | 3.1% |
| Renault Trafic | 2014–2017 | 2.9% |
| Vauxhall Vivaro | 2018–2021 | 2.9% |
| Vauxhall Vivaro | 2014–2017 | 2.7% |
| Mercedes-Benz Vito | 2014–2017 | 2.7% |
| Renault Trafic | 2018–2021 | 2.6% |
| Ford Ranger | 2010–2013 | 2.6% |
| Fiat Doblo | 2018–2021 | 2.6% |
| Mercedes-Benz X | 2018–2021 | 2.6% |
| Volkswagen Sharan | 2010–2013 | 2.5% |
| Ford Transit Connect | 2018–2021 | 2.4% |
| Citroen Relay | 2010–2013 | 2.4% |
| Ford Ranger | 2014–2017 | 2.3% |
| Volkswagen Amarok | 2018–2021 | 2.3% |
| Mercedes-Benz S-Class | 2010–2013 | 2.3% |
| Volkswagen Caddy | 2014–2017 | 2.2% |
| Mercedes-Benz ML | 2010–2013 | 2.2% |
Showing the worst 20 of 128 affected model-and-year combinations. The full dataset is downloadable below.
Which manufacturers it clusters on
Pooled across each make's whole range, so this is a fact about the brand rather than about one of its models. Makes with at least 50,000 tests.
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See whether the car you're looking at has this on record
Type the registration and you get that car's own MOT history — every advisory and every failure, including whether this one has already come up.
Source: DVSA anonymised MOT tests and results, 2023. Class 4 standard tests only. Contains public sector information licensed under the Open Government Licence v3.0.