The area in which drivers of older, more polluting vehicles are liable for the sum will be 18 times larger from next week.
For diesel cars to avoid the charge they must generally have been first registered after September 2015, while most petrol models registered from 2005 are also exempt.
The Ultra Low Emission Zone (Ulez) has operated since April 2019, covering the same area of central London as the Congestion Charge.
It is being expanded from Monday October 25 to include all areas within the North and South Circular roads.
Transport for London (TfL) said nearly 10 million people have used its online checker to find out whether they will be charged if they drive into the zone.
It wants more people to use the tool before next week’s extension.
Some 100,000 cars, 35,000 vans and 3,000 lorries could “potentially be affected” by the new rules every day, according to TfL estimates.
The transport body added that more than 80% of vehicles in the wider zone will not be charged, up from 39% in February 2017 when the plans for the expansion were first announced.
More than one million letters have been sent to people who have driven within the new boundaries to make them aware of the changes, while more than 600,000 leaflets have been delivered to residents living there.
The charge applies all day, every day, except on Christmas Day.
“The Ultra Low Emission Zone has already cut nitrogen dioxide pollution by nearly half in central London and the expansion of the zone on October 25 means many more Londoners across the city will enjoy the benefits of cleaner, healthier air.
“We need bold action to clean up London’s air and whilst it’s encouraging that four out of five vehicles now meet the current standards and won’t have to pay the Ulez charge, I advise all drivers to use the TfL checker to make sure your vehicle is Ulez compliant.
“Our scrappage scheme will continue supporting motorists to ditch their polluting cars and make the switch to greener forms of transport as we drive towards a green recovery.”
Small businesses, charities and Londoners who are disabled or on low incomes who scrap a non-compliant cars and purchase a cleaner vehicles can apply to TfL for a £2,000 grant.
Those scrapping a motorcycle or moped may be eligible for a £1,000 payment.
Schemes for vans, minibuses and lorries have been suspended due to “unprecedented demand and limited funds”.
Alex Williams, TfL’s director of city planning, said: “We don’t want drivers to get caught out on October 25, we are advising people to use our checker to see if their vehicle meets the standards.
“If they are liable for the charge we would ask them to consider using public transport, or to walk or cycle if possible, and if they need to drive, consider using a car club whose fleets are fully Ulez compliant, or switching to the cleanest vehicle.”