How to Troubleshoot a Cam Sensor on a 1994 Audi


1. Remove the concealment covering the engine, using the appropriate nut driver.
2. Locate the camshaft sensor on the rear left side of the cylinder head. Connect the graphing meter's black lead to a good ground and use the red lead as a probe to test the far, left wire on the sensor. Turn the ignition key on. Turn the meter to volts and probe the ground wire on the sensor connector. The meter's display should show less than 100Mv. If the reading is higher, replace the cam sensor.
3. Unplug the sensor connector. Probe the center wire on the harness, which is the signal return wire. The reading should be around five volts, plus or minus one-half volt. If the voltage is higher or lower there is a problem with either the computer or wiring, not with the sensor.
4. Turn the key off and plug the connector back into the sensor.
5. Place the meter on graphing and leave the black lead connected to a good ground. Start the engine and probe the center wire on the sensor connector. The graph should show evenly spaced rectangular towers with no glitches or dropouts. If they are irregular, replace the sensor.
6. Place the meter on frequency and probe the center wire again. The meter should display 7Mh, plus or minus 1Mh. The frequency should also rise steadily as the rpm increases with no fluctuations or irregularities. If you see any irregularities, replace the sensor. If there are no irregularities, the sensor is good.