Aisin AW 80-40LE

Aisin's small transverse four-speed — in the Chevrolet Aveo and Spark.

It is the smallest automatic in this catalogue, in cars whose owners very often meet an automatic gearbox fault for the first time — which is the reason to be plain about what a symptom costs.

Its recurring failure is the solenoid and the valve body, producing a harsh or delayed engagement into drive, a change arriving at the wrong speed, or a limp mode locked in third. All three read as terminal on a small, cheap car and usually are not, and the solenoids are serviceable from the pan.

Fluid is Dexron and the interval is real — these predate sealed-for-life entirely, so the service was specified and is simply often skipped. On a car of this value that is what decides whether the transmission is worth repairing, and it is worth establishing before anything is quoted.