Fault phenomenon: a Audi A6L car, the indicator light occasionally flickers, but there is no other unusual feeling when driving. Fault diagnosis: after repeated inspection, it is found that the gap between the spark plug electrodes is too large and the ignition energy is increased and the electromagnetic interference is generated, and the control unit of the automatic transmission is misjudged. For cars with more mileage (especially long distance), if this kind of fault occurs, the spark plugs should be checked first. The excessive gap between the electrodes of the spark plug is a common reason. Troubleshooting: replace the spark plug.