Delivered between 2001 and 2003, the cars displaced R40s and R42s that operated on the L service in conjunction with the BMT Canarsie Line's signal system being automated.

The 212 cars were expected to provide enough service for years, but the fast growth of the Williamsburg neighborhood overloaded the L by mid-2006,[6] which resulted in some R160s being placed on the line.

Unlike the rest of the NTT fleet at the time, the R143s are equipped with interior LED screens, which take the place of the MTA Arts for Transit cards that are usually located there.

However, the LCD screens have the capability to display multiple colors instead of only red, orange, and green.

[11][12] The CBTC equipment used in the Canarsie Line cars was manufactured by Siemens Transportation Systems.

The new cars would be expected to have automatic PA announcements, high efficiency lighting, emergency intercom and customer alarms, AC propulsion motors, speedometers and event recorders, electronic information display signs, artwork, a central diagnostics monitoring system, microprocessor-controlled air compressor, brake and communication systems, roof-mounted microprocessor-controlled HVAC, and to be compliant with ADA requirements.

[23] On April 18, 2004, an eight-car R143 train overshot the bumper at Eighth Avenue after the operator suffered a possible seizure.

On June 21, 2006, another eight-car R143 train overshot the bumper, this time at the end of the tracks in the Canarsie Yard after the operator suffered a seizure.

The other cars in the set (8278–8280) suffered minor body damage and were moved to the 207th Street Yard and repaired.

[26] In 2017, a set of R143s was equipped with measuring gauges to test out the curve radius and gangway flex in the existing 60-foot (18.29 m)-long cars in order to collect data for evaluating the R211T order,[27] which began running in revenue service on February 1, 2024.