Possible Cause & Correction

Check for obvious overheating problems:

• Low coolant.
• Loose water pump belt.
• Restricted airflow to radiator, or restricted water flow through radiator.
• Fuel quality (proper octane rating).
• Correct PROM (MEM-CAL).
• Closed thermostatic air cleaner device.
• Ignition timing (ESC check).
• Low fuel system pressure. See the CHART A6 - FUEL SYSTEM PRESSURE TEST in the TBI TESTS/CODES article in this section.
• EGR system not opening. See EGR SYSTEM CHECK chart.
• Proper transmission shift points and TCC operation. See TORQUE CONVERTER CLUTCH chart in the TBI TESTS/CODES article in this section.
• Incorrect engine parts (camshaft, cylinder heads, pistons, etc.).
• Remove carbon with Top Engine Cleaner (12345089).
• On vehicles over 8500 GVW with 5.7L or 7.4L engine and dual catalytic converter system, check for exhaust restriction in rear converter area.