The following notice has been issued by the manufacturer:

POSSIBLE RISK OF GAS LEAK with gas connection fitting on two models of built-in gas hobs.
Owners of affected gas hobs are requested to comply with the following safety notice.

In the United Kingdom the following named built-in gas hobs from the production period are affected:

Bosch model: NGU4151DB (produced January 2009 – October 2011)
Neff model: T20S31N0 (produced January 2009 – October 2011)

Due to potential damage to installed gas connectors, in certain circumstances gas can escape in an uncontrolled manner and in extremely rare cases a risk of explosion can arise.

To avoid any potential hazard, owners of an affected appliance should turn off the gas supply to the appliance immediately and not use it until the connection fitting has been replaced.
BSH is offering every owner of an affected appliance a free replacement of the gas connector by an authorised service engineer at the owner’s home. BSH requests all customers of a product listed above to check whether their appliance is affected by this safety campaign.
We apologise for any inconveniences caused and thank you for your understanding and patience. Please call us in case you have problems with checking whether your appliance is affected or you have any further questions.

  1. Check whether your gas hob is affected as follows:Look carefully at the gas hob shown above. If it is similar to your gas hob check whether it is affected by the voluntary safety measure.
    Further details to assist with identifying affected appliances and visual guides can be found here for Bosch and herefor NEFF.
    Please note down the model number (E-Nr.) and the four digits batch number (FD) on the type plate of your appliance (see figures below).

    Built-in Gas Hobs

    One Bosch and one Neff 60 cm wide built-in gas hob with control knobs on the right may be affected (Bosch model: NGU4151DB / Neff model: T20S31N0)

    Built-in Gas Hobs

  2. To determine whether your gas hob is actually affected, please enter these numbers into the following website.

Source & More Info
Source & More Info 2

Safety Notice: Built in gas hobs (Bosch) / (Neff)