CTS V6-3.2L VIN N (2003)
tester. Contaminants in the fuel composition tester could result in misdiagnosis.
9. Observe the diagnostic LEDs on the fuel composition tester.
If the red fuel diagnostic LED is illuminated, a fuel contamination condition exists. Refer to Fuel System Cleaning.
10. Measure the output frequency of the fuel composition tester.
11. Subtract 50 from the reading on the DMM to obtain the percentage of alcohol in the fuel sample. Refer to the examples in the table.
12. If the fuel sample contains more than 10 percent ethanol, replace the fuel in the vehicle.
