Skip advert
Advertisement

Diesel Head filler cap

Avoid misfuelling misery by fitting a new filler cap.

Diesel Head filler cap

Price: £34.99 (standard); £39.99 (lockable)
Contact: 0121 236 6144, www.dieselhead.co.uk

There’s no way you can misfuel your diesel car with petrol if you fit the Diesel Head. This clever device replaces your standard filler cap, and prevents narrower petrol pump nozzles entering your tank.

Installation is simple. Unscrew the factory-fitted cap and place the Diesel Head over the filler neck, then tighten its three screws. Spare screws and a hex key are included in the box, as are simple fitting instructions, and our test car’s filler flap shut easily with the product in place.

Advertisement - Article continues below

The mechanism in the Diesel Head has four catches, each at 90-degree intervals. When the widest points of the fuel nozzle touch the first two spring-loaded clips (opposite each other), the next two open up, allowing you to start fuelling.

Once you’re finished, take the nozzle out and the clips spring shut in turn, locking again. At £34.99, it’s not cheap, but misfuelling repairs can cost hundreds.

Just don’t be tempted to fiddle with the mechanism before fitting – the catches have to close in a preset order, otherwise you can insert a petrol nozzle.

Verdict

Rating: ★★★★
What is it?
Gadget to prevent you from putting petrol into your diesel tank.
Problems?
Pricey, mechanism can be tricked when not fitted.
Why buy?
Simple to fit, discreet, effective solution.

Skip advert
Advertisement

New & used car deals

Toyota Yaris Cross

Toyota Yaris Cross

RRP £26,495Avg. savings £1,672 off RRP*Used from £12,200
Vauxhall Corsa

Vauxhall Corsa

RRP £19,200Avg. savings £4,670 off RRP*Used from £16,745
Nissan Juke

Nissan Juke

RRP £19,785Avg. savings £4,364 off RRP*Used from £9,500
Renault Clio

Renault Clio

RRP £16,160Avg. savings £2,721 off RRP*Used from £8,800
* Average savings are calculated daily based on the best dealer prices on Auto Express vs manufacturer RRP
Skip advert
Advertisement

Most Popular

New Peugeot 208 GTi: electric hot hatch gets stunning looks and plenty of power
Peugeot E-208 GTi - reveal front

New Peugeot 208 GTi: electric hot hatch gets stunning looks and plenty of power

Hot Peugeot E-208 gets racier styling, 276bhp and does 0-62mph in just 5.7 seconds
News
13 Jun 2025
New BYD Dolphin Surf Comfort review: the best BYD yet
BYD Dolphin Surf Comfort - front

New BYD Dolphin Surf Comfort review: the best BYD yet

The new BYD Dolphin Surf Comfort is arguably the Chinese brand's most convincing model in its range
Road tests
11 Jun 2025
New entry-level Renault Symbioz is £3k cheaper than a Nissan Qashqai
Renault Symbioz hybrid - front angled

New entry-level Renault Symbioz is £3k cheaper than a Nissan Qashqai

The Renault Captur has also been fitted the new full-hybrid powertrain, which gets a bigger battery for more pure-electric driving
News
12 Jun 2025