N42 & N46

The N46 was a revised N42 introduced with the 118i and 120i in late 2004 and fitted to the last year of E46 production. The N42 and N46 are so similar they can be interchanged if the engine wiring loom has been swapped over – so an N42 bare engine can be used in an E90 3-Series or 1-Series and vice versa. The Valvetronic ECU was discontinued on the N46, with Valvetronic control being taken care of by the engine ECU. The air injection emissions system was discontinued on the very last batch of N42 units in readiness for the N46.