944 L4-2681cc 2.7L (1989)
Tool Calibration
4. If the display is outside of the test value of 4.0 +/- 0.3 scale values, readjust the gage dial. This is done by turning the calibration screw with a
small screwdriver until the specified value of 4.0 scale units is reached. In so doing the gage 9201/2 remains between the test sensor of the tester.
5. Recheck after finishing calibration.