Circuit Description
WARNING: This page is about a different car, the 2003 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
ECM uses signals provided by crankshaft and camshaft position sensors to monitor changes in crankshaft rotation for each cylinder. If engine speed rate has changed enough to equal a preset number, a misfire is detected and MIL is illuminated. If misfire rate is great enough, and driving conditions will cause catalytic converter damage or overheating, MIL blinks when a misfire is occurring. DTC P0300 is set when misfiring of random cylinders is detected during any particular 200 or 1000 revolutions. DTCs P0301-P0306 will set when misfiring of respective cylinder is detected during any particular 200 or 1000 revolutions. Possible causes are:
- Open or short in engine wiring.
- Poor contact at ECM or component.
- Vacuum hose(s) damaged, cracked or disconnected.
- Ignition system malfunction.
- Defective fuel injector(s).
- Improper fuel pressure.
- Defective Mass Airflow (MAF) meter.
- Defective Engine Coolant Temperature (ECT) sensor.
- Defective engine compression.
- Improper valve clearance.
- Improper valve timing.
- Defective PCV hose connection.
- Defective PCV hose.
- Defective ECM.