Catalytic converter missing or not working
How it can appear on an MOT certificate
- “Catalytic converter missing where one was fitted as standard”
- “Catalytic converter obviously defective”
What it is
The catalytic converter cleans harmful gases in the exhaust. Cars fitted with one as standard must still have it.
Why it matters
A missing or failed converter means much higher emissions. Catalytic converters are also a target for theft.
What to check when viewing a car
Ask whether the converter has ever been replaced. A sudden loud exhaust note can be a sign one has been removed.
Has the car you're looking at had this before?
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What the MOT categories mean
- Dangerous
- A direct and immediate risk to road safety, or a serious impact on the environment. The car fails and shouldn't be driven until it's repaired.
- Major
- It may affect the car's safety, put other road users at risk or harm the environment. The car fails and should be repaired straight away.
- Minor
- No significant effect on safety or the environment. The car passes, but it should be repaired as soon as possible.
- Advisory
- Something to keep an eye on that could need repairing in future. The car passes.
Related: exhaust and emissions
- Exhaust leak
- Exhaust insecure or mountings damaged
- Emissions over the limit
- Diesel smoke over the limit
- Engine warning light (MIL) on
Buying a used car?
General information about this type of MOT defect, not advice about a particular car. How serious it is depends on the car; have any car you're buying inspected by a qualified mechanic.