Symptom Checks

Perform the following:

• Perform Key On Engine Off (KOEO) Self-Test. See step  1 of DIAGNOSTIC SUB-ROUTINES.
• Check power to MAP/BARO sensor. See step 3) of CIRCUIT TEST S in appropriate TESTS W/CODES article in the ENGINE PERFORMANCE Section.
• Check idle speed. See IDLE SPEED in ADJUSTMENTS article in the ENGINE PERFORMANCE Section.
• Check ignition system. See IGNITION SYSTEMS in appropriate I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
• Check Positive Crankcase Ventilation (PCV) system. See EMISSION SYSTEMS & SUB-SYSTEMS in appropriate I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
• Ensure driveline and transmission are functioning properly.
• Check air intake system. Ensure throttle plate and linkages operate properly.
• Check fuel delivery system. See FUEL SYSTEM in appropriate I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
• Check for restricted exhaust system.
• Check EGR system. See EMISSION SYSTEMS & SUB-SYSTEMS in appropriate I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
• Check Fuel Evaporation (EVAP) system. See EMISSION SYSTEMS & SUB-SYSTEMS in appropriate I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
• Check engine mechanical condition. Check compression, camshaft, valve train components, etc.
• Check Heated Oxygen Sensor (HO2S) heater. Go to step 21) of CIRCUIT TEST H in appropriate TESTS W/CODES article in the ENGINE PERFORMANCE Section.
• Cooling system (radiator, thermostat, etc.)
• Check customer driving habits (over RPM/speed limiting function enabled).