Poor Fuel Economy: Sensor/System
WARNING: This page is about a different car, the 2003 Pontiac Sunfire, 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, and 2003 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
- Check for the following that may cause the engine to run rich:
- Any water intrusion in the HO2S connector.
- The engine oil contaminated by fuel.
- An EVAP canister purge condition.
- Incorrect fuel pressure. Go to FUEL PRESSURE TEST under FUEL SYSTEMS (GASOLINE) in BASIC DIAGNOSTIC PROCEDURES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
- A leaking fuel pressure regulator. Go to FUEL SYSTEM DIAGNOSIS (GASOLINE) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
- Any leaking fuel injectors. Go to FUEL SYSTEM DIAGNOSIS (GASOLINE) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
- Any vacuum hoses that are split, kinked, or improperly connected.
- An air intake duct that is collapsed or restricted.
- An air filter that is dirty or restricted.
- Check the air intake system and crankcase for air leaks.
- Check for an Engine Coolant Temperature (ECT) sensor that has shifted in value. Go to TEMPERATURE VS. RESISTANCE table.
- Check the crankcase ventilation system for proper operation.
- Check for an inaccurate speedometer.
- Use a scan tool to monitor the Knock Sensor (KS) system for excessive spark retard activity.