Also known as: 4hp20, 4hp-20, zf 4hp20, zf transverse 4-speed
ZF's transverse four-speed — in the Peugeot 307 and 407.
It is not the AL4/DP0, PSA's own four-speed that appears in the same cars in the same years. The two are routinely conflated, including in parts listings, and they share neither internals nor fluid — so the first question about a four-speed automatic Peugeot is which of the two is fitted.
Nor is it the 4HP22, ZF's longitudinal four-speed of nearly the same name in Land Rovers and BMWs. Three gearboxes, two of them ZF's own, and a naming scheme that separates them by one digit.
Its recurring failure is the valve body and the solenoids, presenting as a harsh or delayed engagement and a change that arrives late. The fluid specification is ZF's and not a generic Dexron, and on a car of this age the fluid's history is unknowable and usually poor — which is why a service comes before a diagnosis rather than after one.
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.
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