DEFINITION: The vehicle's fuel economy, as measured by an actual road test, is noticeably lower than expected. Also, the fuel economy is noticeably lower than the fuel economy was on this vehicle at one time, as previously shown by an actual road test.

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

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Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

1. Perform a bulletin search.
2. If a bulletin that addresses the symptom is present, correct the condition as instructed in the bulletin.

Did you find a bulletin that addresses the symptom?

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Go to Step 16

Go to Step 3

Did you perform a visual/physical check?

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Go to Step 4

Go to Symptoms for the Visual /Physical Check.

Check the owner's driving habits.

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Go to Step 5

Go to Step 6

Review the items in step 4 with the customer and advise as necessary.

Is the action complete?

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System OK

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1. Visually/physically check the vacuum hoses for the following conditions:

•

Splits

•

Kinks

•	Improper connections and routing as shown on the Vehicle Emission Control Information label.

2. If a problem is present, repair as necessary.

Did you make a repair?

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Go to Step 16

Go to Step 7

1. Remove and check the air filter element for dirt or for a possible restriction.
2. Replace the air filter element if necessary.

Did you make a repair?

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Go to Step 16

Go to Step 8

1. Check the engine coolant level for being low. Refer to Engine Cooling.
2. If a problem is present, repair as necessary.

Did you find a problem?

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Go to Step 13

Go to Step 9

1. Check for an incorrect or malfunctioning engine thermostat. Refer to Engine Cooling.
2. If a problem is present, repair as necessary.

Did you find a problem?

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Go to Step 13

Go to Step 10

1. Check in Engine Mechanical for the following problems:

•	Low compression

•	Sticking valves

•	Hydraulic valve lifter problem

•	Leaking cylinder head gaskets

•	Worn or incorrect camshaft

•	Incorrect cam timing

•	Damaged timing belt

2. If a problem is present, repair as necessary.

Did you find a problem?

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Go to Step 13

Go to Step 11

1. Check the TCC operation. Refer to Transmission Fluid Check .
2. If a problem is present, repair as necessary.

Did you find a problem?

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Go to Step 13

Go to Step 12

1. Check the exhaust system for a possible restriction:

•	Inspect the exhaust system for any damaged or collapsed pipes.

•	Inspect the muffler for heat distress or for a possible internal failure.

•	Check the exhaust system back pressure for a possible plugged catalytic converter. Refer to Restricted Exhaust System Check .

2. If a problem is present, repair as necessary.

Did you find a problem?

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Go to Step 15

Go to Step 13

1. Check for any air leaks in the following areas:

•	The throttle body mounting area

•	The mass air flow (MAF) sensor

•	The duct work between the MAF and the throttle body

•	The intake manifold sealing surfaces

2. If a problem is present, repair as necessary.

Did you find a problem?

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Go to Step 15

Go to Step 14

1. Review all of the diagnostic procedures within this table.
2. When all of the procedures have been completed and no malfunctions are found, review/inspect the following:

•	The scan tool data

•	The Freeze Frame data

•	All of the connections within a suspected circuit and/or system

3. If a problem is present, repair as necessary.

Did you find a problem?

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Go to Step 15

Go to Step 3

Operate the vehicle under the same conditions (as closely as possible) as when the original symptom occurred.

Is the original symptom still present?

Go to Step 3

Go to Step 16

Are any other driveability symptoms still present?

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Go to Symptoms

System OK