Will a Steering Wheel Spinner Knob Fail an MOT?
You’ve fitted a steering wheel spinner knob — or you’re thinking about fitting one — and your MOT is coming up. The question is straightforward: will it cause a failure?
The direct answer: A steering wheel spinner knob will not cause an MOT failure on its own. It is not listed as a specific inspection item in the DVSA MOT inspection manual, and there is no test category for steering wheel accessories. However, any attachment to the steering wheel that compromises steering operation, security, or driver control could be flagged as a deficiency under the broader steering system inspection criteria.
In practice, this means a properly fitted spinner knob that is secure, does not obstruct the steering mechanism, and does not interfere with any controls will pass without issue. A loose, damaged, or obstructive one could attract attention.
This article explains exactly what MOT testers inspect, where a spinner knob sits within that inspection framework, and what — if anything — you should do before taking your vehicle in.
What the MOT Actually Tests on the Steering System
The MOT test in Great Britain is governed by the Driver and Vehicle Standards Agency (DVSA). The inspection criteria are published in the MOT Inspection Manual — a publicly available document that defines every item a tester must examine, and the standards each item must meet.
Steering is covered under Section 2: Steering of the inspection manual.
The key areas tested are:
2.1 — Steering Wheel and Column
This is the section most relevant to spinner knobs. The tester inspects:
- Steering wheel security — Is the steering wheel firmly attached to the column? Does it have excessive play or movement at the hub?
- Steering wheel condition — Is the wheel itself in a condition that allows safe control? (Cracked, broken, or deformed wheels fail.)
- Steering column — Is the column secure, free from excessive wear, and operating correctly?
- Steering lock — Does the steering lock (if fitted) operate without jamming or interfering with steering?
What the tester is NOT inspecting in this section:
- Whether you have accessories attached to the steering wheel
- Whether your steering wheel is standard or aftermarket (provided it meets the criteria above)
- Whether you have a spinner knob, steering cover, or any other removable accessory
The inspection concerns the function and security of the steering system, not the accessories clamped to the rim.
Source: DVSA MOT Inspection Manual — Section 2.1, Steering Wheel and Column. The manual is publicly available on GOV.UK. (MOT inspection manual: cars and passenger vehicles — GOV.UK)
2.2 — Steering Mechanism and Components
This covers the mechanical steering components beneath and beyond the wheel:
- Steering rack and pinion (or steering box)
- Track rod ends and ball joints
- Power steering pump and fluid (where applicable)
- Steering gaiters and boots
- Universal joints in the steering column
A spinner knob has no connection to, and no effect on, any of these components. It is clamped to the outer rim of the steering wheel and does not interact with the steering mechanism.
2.3 — Power Steering
The tester checks that the power steering system is functioning, that there are no fluid leaks, and that assistance is provided when the engine is running.
Again, a spinner knob is irrelevant to this inspection item.
The Three MOT Deficiency Categories
Since May 2018, the MOT test in the UK uses three categories of deficiency, aligned with EU Directive 2014/45/EU (retained in UK law post-Brexit):
Minor – A defect that has no significant effect on the safety of the vehicle or impact on the environment. – Pass (noted on the certificate as an advisory)
Major – A defect that may affect the safety of the vehicle, put other road users at risk, or impact the environment. – Fail
Dangerous – A defect that poses a direct and immediate risk to road safety or has a serious impact on the environment. – Fail (the vehicle must not be driven until repaired)
For a steering wheel spinner knob to result in any deficiency, it would need to fall within a testable inspection item and meet the criteria for one of these categories.
The realistic scenario:
- A secure, properly installed spinner knob → No deficiency. It is not an inspection item.
- A loose spinner knob that moves freely on the rim → Possible minor or advisory note, if the tester considers it could affect steering control. This is at the tester’s discretion.
- A spinner knob that physically obstructs the steering mechanism or prevents full lock-to-lock rotation → Possible major deficiency, because it impairs the function of the steering system. This would be unusual and would require a seriously incorrect installation.
Is a Spinner Knob Considered a “Modification” for MOT Purposes?
This is where some confusion arises, so let’s be precise.
The MOT test does not have a general “modifications” category. There is no section where a tester lists every aftermarket change and assesses each one individually. The test inspects specific systems and components against defined standards.
A steering wheel spinner knob is:
- Not a structural modification (it doesn’t alter the vehicle chassis, body, or frame)
- Not a mechanical modification (it doesn’t change the steering ratio, mechanism, or geometry)
- Not an electrical modification (it has no wiring, no connection to any system)
- Removable (it clamps on and can be removed in seconds without tools in most cases)
It is, in practical terms, a removable accessory — comparable to a gear knob cover, a dashboard phone mount, or a seat cushion. These items are not part of the MOT inspection framework.
Are Steering Wheel Spinner Knobs Legal in the UK?
What MOT Testers Say in Practice
While the official inspection manual is the definitive reference, it’s worth noting how this plays out in real MOT testing bays.
Anecdotal evidence from UK motoring forums (including those on PistonHeads, HonestJohn, and MoneySavingExpert) consistently reports that:
- MOT testers do not ask drivers to remove spinner knobs before testing
- Spinner knobs are not flagged on MOT results as deficiencies, advisories, or notes
- Testers who are asked about spinner knobs typically confirm that they are not an inspection item
- Vehicles with prescribed disability steering aids (including spinner knobs) pass MOT routinely without comment
We must be clear: Individual tester discretion plays a role in any MOT. A tester who encounters something they believe affects vehicle safety has the professional authority to investigate further. If your spinner knob is so loose it’s about to fall off, a conscientious tester may mention it — not because it’s a test item, but because it’s sensible advice.
This is not a failing mark. It’s a professional judgement, the same as a tester mentioning your tyres are legal but getting close to the limit.
What About Prescribed Disability Steering Aids?
If your spinner knob has been prescribed by a Driving Mobility assessment centre or an occupational therapist as a required driving adaptation, it’s important to understand that:
- Prescribed steering aids are expected to be fitted during the MOT. The vehicle should be tested in the condition it is driven. If you drive with a spinner knob as a prescribed aid, it should be present during the test.
- DVSA guidance recognises adapted vehicles. MOT testers encounter adapted vehicles regularly. Adaptations including spinner knobs, left-foot accelerators, hand controls, and steering balls are familiar to experienced testers.
- The V5C (logbook) may note that the vehicle is adapted, depending on the nature and extent of adaptations. A simple spinner knob typically wouldn’t trigger a V5C annotation, but more extensive steering modifications might.
- Motability vehicles undergo MOT testing through standard channels and pass with steering aids fitted as standard.
Source: Driving Mobility provides guidance on vehicle adaptations and testing requirements. (drivingmobility.org.uk)
[Internal Link to: Steering Wheel Spinner Knobs: UK Law, MOT & Insurance – The Complete Guide — the MOT section of the pillar page]
Should You Remove Your Spinner Knob Before an MOT?
No. There is no reason to remove it.
If the knob is properly installed and secure:
- It is not an inspection item
- It does not affect any testable component
- Removing it and refitting it afterwards creates unnecessary work and risks incorrect reinstallation
If the knob is loose or poorly fitted:
- Fix the installation before the MOT — not because of the test, but because a loose object on your steering wheel is a hazard while driving
- A properly tightened clamp on a clean rim is all that’s needed
If your spinner knob is a prescribed disability aid:
- Definitely do not remove it. The vehicle should be tested in the condition you drive it. Removing a prescribed aid could mean the vehicle is tested in a configuration that doesn’t reflect real-world use.
The Relevant Legislation
For those who want the legal underpinning:
The Road Vehicles (Construction and Use) Regulations 1986
- Regulation 29 requires that steering gear be maintained in good and efficient working order and properly adjusted. A spinner knob does not affect the working order or adjustment of steering gear.
- Regulation 100 requires that no vehicle shall be used on the road in such a condition that its use involves a danger of injury to any person. A secure spinner knob on a power-steering-equipped vehicle does not create a danger of injury.
- Regulation 104 covers the requirement to maintain steering gear. Again, a removable accessory on the wheel rim is not part of the steering gear.
Source: The Road Vehicles (Construction and Use) Regulations 1986. (legislation.gov.uk)
[Internal Link to: Are Steering Wheel Spinner Knobs Legal in the UK? — link from Regulation 100 or Regulation 104 reference]
MOT Stations and Disability-Adapted Vehicles: Your Rights
If you use a spinner knob as a prescribed steering aid and an MOT tester asks you to remove it or suggests it is a problem, you should know:
- You can request clarification on which specific inspection item the tester is referencing. The MOT manual is public — the tester must be able to point to a defined criterion.
- You can request a re-test or appeal. If you believe a failure is incorrect, the DVSA operates a formal appeals process. Contact DVSA on 0300 123 9000 or through GOV.UK.
- Disability adaptations are protected. The Equality Act 2010 means that service providers (including MOT testing stations) must not discriminate against disabled people. Refusing to test a vehicle because it has a prescribed steering aid, or failing it without a valid inspection criterion, could constitute discrimination.
This scenario is rare. Most testers are professionals who encounter adapted vehicles regularly and understand the distinction between a prescribed aid and a problematic modification. But it’s worth knowing your position.
Source: Equality Act 2010. (legislation.gov.uk)
Source: DVSA complaints and appeals process. (GOV.UK)
Frequently Asked Questions
Will a steering wheel spinner knob fail an MOT? No. A properly fitted steering wheel spinner knob is not a specific MOT inspection item. It does not affect the steering mechanism, column, or any testable component. It will not cause a failure when securely installed on the steering wheel rim.
Do I need to remove my spinner knob for the MOT? No. There is no requirement to remove it. If it is a prescribed disability aid, you should leave it fitted, as the vehicle should be tested in the condition it is normally driven.
What if the MOT tester says my spinner knob is a problem? Ask the tester to identify the specific inspection item and deficiency category. The DVSA MOT inspection manual is publicly available. If you believe a failure is incorrect, you can appeal through DVSA. Prescribed disability aids are not grounds for MOT failure.
Is a steering wheel spinner knob classed as a vehicle modification for MOT? The MOT does not have a general “modifications” inspection category. It tests specific systems against defined criteria. A removable accessory clamped to the steering wheel rim does not fall within any testable system or component.
Can a loose spinner knob fail an MOT? Not formally, as it is not a defined inspection item. However, a tester who observes a severely loose accessory on the steering wheel may note it as an advisory or raise it as a concern. The solution is simple: ensure the clamp is properly tightened before any journey, not just the MOT.
Do adapted vehicles with spinner knobs pass MOT normally? Yes. Thousands of Motability and privately adapted vehicles pass MOT annually with steering aids fitted, including spinner knobs, steering balls, and other prescribed devices. DVSA testers routinely encounter and accept these adaptations.
