Noise, emissions and leaks
Emissions failure, sensor or valve
Checked on 30 July 2026.ClickMechanic, Car oxygen sensor replacement cost guide (as of 30 July 2026)
What does emissions failure, sensor or valve cost in the UK?
£110 to £650 fitted at an independent garage, VAT included, on a mainstream car. The midpoint of that range is about £380, and where you land inside it is decided by access, parts and wheel size rather than by the garage's postcode.
High emissions are a symptom, not a job, so the first spend is a diagnosis. On petrol the measurements are carbon monoxide, hydrocarbons and lambda, with typical fast idle limits of 0.2 per cent CO, 200ppm HC and lambda between 0.97 and 1.03. On diesel it is smoke opacity in m-1, and a car first used from 1 January 2014 is held to 0.7 where a pre-2008 engine is held to 2.5 or 3.0, which is why an older diesel gets away with a great deal more. The two most common repairs sit inside this range: a lambda sensor at £150 on average within £110 to £220 and about an hour, and an EGR valve at £265 within £150 to £650 and around an hour and a half. Before either, a service with the right oil, a new air filter and a long run at motorway revs sometimes brings a borderline car back under the limit on its own.
How this job compares
| Job | Area | Fitted price |
|---|---|---|
| Front wiper blades | Visibility | £19 to £45 |
| Emissions failure, sensor or valve | Noise, emissions and leaks | £110 to £650 |
| Exhaust section or full system | Noise, emissions and leaks | £100 to £1,200 |
Other noise, emissions and leaks work
| Job | Fitted price | Labour |
|---|---|---|
| Exhaust section or full system | £100 to £1,200 | Not published |
| Catalytic converter | £175 to £900 | 1.2h |
| Diesel particulate filter clean | £160 to £500 | 1.5h |
Common questions
- How much does emissions failure, sensor or valve cost?
- £110 to £650 fitted at an independent garage, including VAT, for a mainstream car.
- How urgent is it?
- The car is usually still drivable, but do not sit on it. Emissions above the manufacturer's limits are a major defect, and an engine running outside its own map wastes fuel and tends to take the catalytic converter with it. Get the cause diagnosed before you buy any parts.
- What moves the price within that range?
- Access, parts and wheel size, mostly. A job that needs the bumper or an arch liner off costs an hour more than the same job on a car where it does not, and a genuine part can be several times an aftermarket one.
- Is this price for one side or both?
- The detail below says where a published price covers a pair. Where it does not, treat the range as one side and expect the second to add less than double, because the labour overlaps.
Sources
Every figure on this page was read off the publisher's own page on the date shown.