Compression Check: Testing and Inspection

Compression, checking





Special tools and equipment
^ 3122 B Spark plug removal tool
^ T10029 Spark plug connector tool
^ VAG1331 Torque wrench 5 to 50 Nm (3.7 to 37 ft. lbs.), or equivalent
^ VAG1763 Compression tester

Test conditions
^ Engine oil temperature must be at least 30°C.
^ Battery voltage must be 11.5 V minimum.

Work sequence
- Remove engine cover.
- Disconnect harness connector -arrow- for ignition coil power output stage.





Only engine code AEG





Engine code AVH, AZG





- Remove fuse 32 from fuse panel.
- Pull connectors off outer injectors.
- Remove spark plug connectors using T10029 tool and place spark plug wires aside.
- Remove spark plugs using 3122 B tool.
- Have a second technician operate starter.
- Vehicles with engine code AEG: fully depress accelerator pedal using a second technician.
- Check compression using VAG1763 tester.

Note: Compression tester operation instructions Tester Operators Manual

- Crank starter until tester shows no further increase in pressure.

Compression pressure:
^ New: 10 to 13 bar (145 to 189 psi)
^ Wear limit: 7.5 bar (109 psi)
^ Maximum permissible difference between all cylinders:
^ 3 bar (43.5 psi)
- Finally, erase engine control module DTC memory because pulling off injector connectors will have caused a DTC to be recorded.
- Check Diagnostic Trouble Code memory, Refer to Powertrain Management
- Check Readiness code.
- Reset Readiness code after DTC's are corrected, Engine Control Module (ECM) is subject to low voltage with ignition on, or ECM is replaced.