Poor Fuel Economy
- Check for fuel leaks.
- Check fuel quality.
- Ensure brakes do not drag.
- Check accelerator pedal linkage.
- Ensure cooling system is functioning properly.
- Check water temperature sensor circuit. See CODE 22 in TESTS W/CODES article.
- Check intake air temperature sensor circuit. See CODE 24 in TESTS W/CODES article.
- Check throttle position sensor circuit. See CODE 41 and CODE 47 in TESTS W/CODES article.
- Check spark plugs.
- Check ignition coil. See SYSTEM/COMP TESTS article.
- Check distributor.
- Check engine compression.
- Check fuel system circuit. See FUEL SYSTEM CIRCUIT chart in TESTS W/CODES article.
- Check injector circuit. See INJECTOR CIRCUIT chart in TESTS W/CODES article.
- Check fuel pressure control vacuum switching valve circuit. See FUEL PRESSURE CONTROL VACUUM SWITCHING VALVE (VSV) CIRCUIT chart in TESTS W/CODES article.
- Check cold start injector circuit. See COLD START INJECTOR CIRCUIT chart in TESTS W/CODES article.
- Check idle speed control valve circuit. See IDLE SPEED CONTROL (ISC) VALVE CIRCUIT chart in TESTS W/CODES article.
- Check neutral start switch circuit. See CODE 51 in TESTS W/CODES article.
- Check main oxygen sensor circuit. See CODE 25 and CODE 26 in TESTS W/CODES article.
- Check sub-oxygen sensor circuit. See CODE 27 and CODE 29 in TESTS W/CODES article.
- Ensure transmission is functioning properly.
- Check engine for mechanical failure.
- Check ECU. See SYSTEM/COMP TESTS article.