The difference in pressure between individual cylinders should not exceed 3.0 bar. If one or more cylinders have a pressure that differs from the pressure in the other cylinders by more than 3.0 bar, this indicates a leak in the cylinder head gasket, damage to the valves, wear of the piston rings or the cylinder running surface. If the wear limit has been reached, the engine must be repaired or replaced.
Execution order
1. To check the compression, the engine oil temperature must be at least +30°C. The oil filter has the temperature of a palm. If the temperature is lower than this, the engine must be warmed up. The engine temperature should not be too high, otherwise the thread in the cylinder head may be damaged when the spark plugs are unscrewed.
2. Turn off the ignition.
3. Remove all spark plugs.
4. Remove the fuel pump fuse.
5. 1.6L engines: Disconnect the injector connectors on both outer cylinders.
6. Engines 1.6: Disconnect the ignition output stage connector. The output stage is connected between the control unit and the ignition coils.
7. Crank the engine with the starter to flush out carbon and soot.
Warning: Set the transmission to neutral and apply the parking brake.
Warning: Do not lean over the engine while cranking it. There is a risk of injury from soot emissions.
8. Screw or press the compression tester into one of the spark plug holes.
9. Ask an assistant to press the gas pedal and hold it in this position during the entire test.
10. Turn the engine over approximately 8 revolutions until the gauge shows no more pressure surges.
11. Check all cylinders in order and compare the obtained values with the required value.
12. When finished, reinstall the spark plugs.
13. Reconnect the output stage connector (1.6L engines).
14. 1.6L engines: Connect the plug connections at the external injectors.
Warning: Due to disconnection of plug connections, faults may be recorded in the engine control unit. It is recommended to have them removed at an AUDI service station as soon as possible.