Also known as: b400, b-600, b600, b-400, aisin b-series
Aisin's B-series six-speed automatics, in light commercial vehicles.
⚑ The number is a TORQUE rating, as it is on Getrag's 420G and Aisin's own 80-40LE — not a model year and not a gear count. A B-600 handles more than a B400 and is a physically larger gearbox.
These are commercial-vehicle units and the duty cycle is the thing that shapes them: heavy loads, frequent stops, long idling, and a service life measured in hours rather than distance. Mileage is a poor guide to condition.
Fluid and its interval decide the outcome. Aisin specifies its own fluid and a shorter interval under load than the base schedule implies, and overheating is the failure mode behind most of what gets reported as a shift fault.
Aisin's TF and TL series are different families for passenger cars, with their own pages here.
Cars fitted with this gearbox
2 generations. Only where a source names the model and the generation together — a gearbox is documented as a product far more often than as a fitment, so this list is deliberately shorter than the truth.
Abarth
Genesis
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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