The B159 cuts off the eastern corner between the A112 and A104 in Leyton.
It starts at traffic lights on the A112 High Road and heads northeast alongside Leyton Green. B159 traffic approaching the A112 cannot turn left; there is a short one-way road past the bus depot along another side of the Green to allow this turning. This road is also mapped as part of the B159 and allows traffic to turn into the A112 in either direction.
The B159 continues on, following the residential Leyton Green Road. This is marked out as S1 (rarely S2) with cycle lanes. After a few bends the road crosses Knotts Green and ends by turning right at traffic lights onto the A104 Lea Bridge Road.