Fuel and Emissions Systems Symptom Troubleshooting
When the vehicle has one of these symptoms, check the Diagnostic Trouble Code (DTC) with the scan tool. If there is no DTC, do the diagnostic procedure for the symptom, in the sequence listed, until you find the cause.Symptom | Diagnostic procedure | Also check for | |
---|---|---|---|
Engine will not start (MIL works OK, no DTCs set) | 1. 2. 3. | Test the battery. Test the starter. Troubleshoot the fuel pump circuit. |
|
Engine will not start (MIL comes on and stays on, or never comes on at all, no DTCs set) | Troubleshoot the MIL circuit. | ||
Engine will not start (immobilizer indicator light stays on or flashes) | Troubleshoot the immobilizer system. | ||
Hard starting (MIL works OK, no DTCs set) | 1. 2. | Test the battery. Check the fuel pressure. |
|
Cold fast idle too low (MIL works OK, no DTCs set) | 1. 2. | Do the ECM/PCM idle learn procedure. Check the idle speed. | |
Cold fast idle too high (MIL works OK, no DTCs set) | 1. 2. 3. 4. | Do the ECM/PCM idle learn procedure. Check the idle speed. Inspect/adjust the throttle cable. Inspect and test the throttle body. | |
Idle speed fluctuates (MIL works OK, no DTCs set) | 1. 2. 3. 4. | Do the ECM/PCM idle learn procedure. Check the idle speed. Inspect/adjust the throttle cable. Inspect and test the throttle body. | Intake air leaks |
After warming up idle speed is below specifications with no load (MIL works OK, no DTCs set) | 1. 2. 3. | Do the ECM/PCM idle learn procedure. Troubleshoot the alternator FR signal circuit. Inspect and test the throttle body. | Vacuum hose clogged/cracked/poor connection |
After warming up idle speed is above specifications with no load (MIL works OK, no DTCs set) | 1. 2. | Do the ECM/PCM idle learn procedure. Troubleshoot the alternator FR signal circuit. |
*: | except KG, KE, KR models |