Even though it's not the most appealing job in the world, paying regular attention to the grease and carbon deposits that build up over time pays dividends and most modern gas barbecues are designed to be easily maintained.
After each meal you should quickly use a scraper or brush and then a damp cloth to remove any food that has attached itself to the grill bars. Cast iron grates will benefit from some cooking oil being wiped over the grill after cleaning.
However, over a period of time deposits will inevitably collect on the burners, flavorizer bars, heat deflectors and other internal surfaces. More thorough cleaning after several meals, or at least twice a year, is therefore recommended.
First of all, lift the lid and inspect the inside. Brush and scrap off any deposits, and then remove any remaining grease and grime with a non-abrasive sponge pad and warm soapy water.
Now it's time for the grill bars. It usually helps to heat these for about ten minutes, then take a scraper and a brush and remove the burnt on deposits. Scrapers should be available as an accessory from the manufacturers along with the appropriate brush which will be brass for cast iron grills or stainless steel.
To complete the job, remove the grill bars, soak them in warm soapy water and then use the sponge pad to wipe them clean before rinsing and drying. It's important not use any toxic chemical degreaser.
With the grill bars removed, you have access to the flavorizer bars and heat deflectors. Clean these using the same technique as for the grill bars with a scraper, brush and soapy water. To remove tough deposits that remain intransigent, you might have to use wire wool.
At the same time, brush the sides and any hard to get places in the interior before paying attention to the burners. Check they are in good working order and none of the holes are blocked, then always using a sideways motion to avoid clogging to brush them clean.
All the detritus will have now found its way to the base of the barbecue. Depending on the model, the bottom tray and / or the drip tray can now be removed, its contents emptied and the tray cleaned or, in the case of a drip tray, replaced.
For the outside of the barbecue, there are dedicated stainless steel cleaners available and these can be applied with a non-abrasive cloth. For all other areas, wiping over with warm soapy water should suffice.