Volkswagen Up/Seat Mii - engine start impaired: Error code 4629

If the vehicles mentioned above experience starting difficulties, various causes may be responsible. Often the engine will not start until the starter is operated for more than 10 seconds. Sometimes several starts are necessary for the engine to start.

The first step is reading out the error memory. Error code 4629 (main relay opens too early) may be stored. (Fig. 1) This leads to the assumption that a relay is faulty. The relays can be reached relatively easily after removing the left cover on the dashboard. (Fig. 2) The position of the main relay(s) should be identified using a relay plan (Fig. 3). One of the relays controls the fuel pump. If the relay is defective, this would explain why the engine does not start.

A weak battery may be another cause of the problem. During the starting process, the vehicle electrical system voltage drops below the threshold at which the fuel pump relay closes. The engine will therefore only start when the vehicle electrical system voltage rises again. In this case, replacing the vehicle battery is a sufficient remedy.

A software update may be considered as a last measure.

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