A604 Sonnax Transmission parts, repair guidelines, problems, manuals

Transmission general data

Number of gears Transmission Type Drive ATF (full capacity) L ATF (change) L ATF type
4 AT FWD 8,6 3,8 Mopar ATF+3
Related transmission models or modifications of this transmission:

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Technical issues and repair guidelines

The A604 transmission is one of the first gearboxes with added electronic computer responsible for all automatics of the hydraulics control, which adapts to the driving style and enhancing efficiency of operation of all transmission elements, including the torque converter (TC). Many spare parts can be replaced by parts for A606 (42LE) produced in 1993. In 2003, the A604 was updated one more time and renamed to 40ТЕ (for engines up to 2.4L), enhanced and well-known 41TE (up to 3.8 L).


For scheduled major repairs specialists usually include: filter, repair kits of gaskets and seals and frictions.

Typical problems are related to:

-Rear planetary gear

- Rear sun gear (wear-out of gears spline connections)

- Hub for friction clutches 2-4 with a sun gear.

- The set of hollow discs is replaced (reason: overheating, vibrations, ageing, contaminated oil with metal parts from shafts.

- The set of bearings is also replaced quite frequently.


The TC has a short operating resource. It should be handed in for repair with cutting and welding after 100-120 thousand kilometers (especially on powerful vehicles). The operation with the worn-out TC lock-up leads to beats and vibrations resulting in breakdown of the bushing and the pump seal.Typical repair of the “old” А604 consists of change of all bushings. This problem occurs when vibrations wear out bushings and oil dropping through bushings lead to the oil starvation.

Old automatic gearboxes have some issues with:

- Replacement of shaft rotation sensors

- Switch\ range sensor.

- different problems with differential bearings

- Rubber-covered piston

- Drum


This transmission reliably operates for a long period of time under the condition of yearly (or after 30 thousand kilometers) oil change and monitoring of its level and quality. If the oil is contaminated very rapidly, then it is advisable to check the TC operation and repair it on a timely basis.