Engine management system check (Every 12 months - regardless of mileage)

Routine maintenance and servicing / Engine management system check (Every 12 months - regardless of mileage)

1 This check is part of the manufacturer’s maintenance schedule, and involves testing the engine management system using special dedicated test equipment. Any fault codes stored in the ECU memory are extracted via a diagnostic socket (mounted on the dashboard underneath the glovebox) and interpreted electronically (see illustration).

13.1 Dashboard mounted diagnostic connector (arrowed)

2 Unless a fault is suspected, this test is not essential, although it should be noted that it is recommended by the manufacturer.

3 The engine management system has the ability to ‘override’ some component failures by reverting to a ‘limp-home’ or ‘backup’ mode. Because of this, component failure may not always be immediately obvious, although some side-effects may be noticed; such as poor fuel economy, poor staring or hesitant acceleration. Having the fault log read electronically by a VW dealer will establish whether any such failures have occurred.

Caution: Although the VW Polo has a diagnostic socket, there is no safe method of extracting the fault code information without using dedicated test equipment.

The use of improvised tools for this purpose may result in internal damage to the engine management system electronic control unit.

4 If access to suitable test equipment is not possible, make a thorough check of all ignition, fuel and emission control system components, hoses, and wiring, for security and obvious signs of damage. Further details of the fuel system, emission control system and ignition system can be found in Chapter 4A, B and C and Chapter 5B.