Nitrox NPC500 Catalytic Converter Petrol Cleaner, 500 ml

Nitrox NPC500 Catalytic Converter Petrol Cleaner is a 500 ml liquid additive intended to be poured into a petrol fuel tank. The listing says it cleans deposits across the engine, fuel and exhaust system, but describes these effects as claims rather than guaranteed outcomes.

At a glance

The liquid is designed to be poured directly into the fuel tank, according to the listing.
The manufacturer describes it as cleaning deposits in the engine, fuel and exhaust system.
The listing positions it for use before an MOT emissions test, without guaranteeing a pass.

Price

£11.89Save 15%

Reference price: ~~£13.99~~

Price checked: 12 Nov 2026

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Often bought together

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£2.75

STP Ultra 5 in 1 Petrol System Cleaner 400ml, Enhances Fuel Economy | Restores Power and Protects your Engine, Mechanical Car Cleaning Products, Concentrated Cleaning Formula, Made in the UK

£10.98

Pros and cons

Pros

A simple pour-in application avoids a separate cleaning tool or installation step.
The 500 ml single-item pack is clearly identified in the product details.

Technical specifications

8 specifications

Identity
Brand	Nitrox
Model	NPC500
Item type	System Cleaner

Contents and form
Capacity	500 Millilitres
Item form	Liquid
Scent	Unscented
Number of items	1
Weight listed	17 Ounces

What to know before buying

Listing details to confirm

Application is described as pouring the cleaner into the fuel tank. Follow the product label for vehicle suitability and use instructions. The listing claims that it cleans deposits and may support emissions results, but does not establish that it will resolve an engine fault or ensure an MOT pass. Customer feedback is positive overall but effectiveness and engine management light experiences are mixed.

What’s in the box

Included

Nitrox NPC500 catalytic converter and petrol fuel cleaner
Exhaust system cleaner, 500 ml

Who is it for?

A good fit for

Petrol vehicle owners looking for a pour-in fuel-system cleaner and who will follow the product label.
Drivers considering a fuel additive ahead of an emissions test, with realistic expectations about the listing's unguaranteed claims.

Less suited to

Buyers seeking a guaranteed MOT pass, a confirmed repair for an engine management light, or a substitute for diagnosing a vehicle fault.

Nitrox NPC500 Catalytic Converter Petrol Cleaner, 500 ml · photo 2 — Additional product photo 2

Customer reviews on Amazon

4.3 / 5 · 585 ratings

5 stars65%65%
4 stars16%16%
3 stars13%13%
2 stars3%3%
1 star3%3%

Customer feedback describes noticeable results, easier use, smoother running, and perceived improvements in fuel consumption and emissions. Some customers say it helped with MOT tests, but this is not a guarantee. Reports about effectiveness and engine management lights are mixed. These perceptions may be relevant if considering the cleaner as routine fuel-system treatment, but they do not establish that it will correct a fault or deliver a particular emissions result.

Positive themes

Customers report ease of use and smoother running.
Feedback mentions perceived improvements in emissions and fuel consumption.

Mixed feedback

Feedback on effectiveness is mixed.
Experiences involving engine management lights are mixed.

Frequently asked questions

How is the Nitrox NPC500 used?

The listing says to pour it directly into the fuel tank. Check the product label for detailed directions and vehicle suitability.

Does it guarantee an MOT emissions pass?

No. The listing says it is intended to help before an MOT, but does not guarantee a pass.

Will it fix an engine management light?

That is not established. Customer feedback reports mixed experiences with engine management lights, so a warning should not be treated as resolved by the additive.