1. Test fuel composition using the J 44175 Fuel Composition Tester and the Instruction Manual.
2. Record the frequency from the special tool test.
3. Compare the special tool test frequency and the Fuel Comp. Sensor Frequency parameter on the scan tool.

Is the difference between the two frequencies less than the specified value?

12 Hz

Go to Step 2

Go to Step 3

1. Clean the fuel system. Refer to Fuel System Cleaning .
2. Replace the fuel filter. Refer to Fuel Filter Replacement .

Did you complete the actions?

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Go to Step 4

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Replace the FCS. Refer to Fuel Composition Sensor Replacement .

Did you complete the replacement?

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Go to Step 4

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1. Reassemble the vehicle as necessary.
2. Clear any DTCs with a scan tool.
3. Start the engine.
4. Operate the vehicle in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 5

Observe the DTC Info with a scan tool.

Are there any DTCs that have not been diagnosed?

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Go to Diagnostic Trouble Code (DTC) List

System OK