Low Idle Speed
- Check water temperature sensor circuit. See CODE 22 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 EGR system. See CODE 71 in TESTS W/CODES article.
- 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 ECU. See SYSTEM/COMP TESTS article.