Possible Causes & Corrections
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Check the following items:
- Inspect air filter for dirt or being plugged.
- Inspect for an air leak in the charge air cooler with a Charge Air Cooler Tester (J-46091).
- Inspect vacuum hoses for splits, restrictions, and improper connections.
- Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 6.6L SIERRA & SILVERADO - DIESEL article.
- Inspect air conditioning system for proper operation. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
- Inspect tires for correct air pressure.
- Inspect driver's driving habits.
- Are heavy loads being carried?
- Suggest to driver to fill the fuel tank and inspect the fuel economy.
- Suggest to driver to read the Important Facts on Fuel Economy in the Owner's Manual.
- Check fuel type and quality.
- Inspect engine coolant level.
- Inspect engine thermostat for always being open or for wrong heat range.
- Inspect transmission for proper operation.
- Inspect Torque Converter Clutch (TCC) operation. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS. When TCC is commanded ON, a scan tool should indicate an RPM drop.
- Inspect Service Bulletins for control module software updates.
- Inspect brake for proper operation.