When the vehicle has one of these symptoms, check for a diagnostic trouble code (DTC) with the HDS. 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. Bleed the fuel system.	Low compression Intake air leaks Locked up engine Broken cam chain Contaminated fuel
Engine will not start (MIL comes on and stays on, or never comes on at all, no DTCs set)	Troubleshoot the DLC circuit.
MIL comes on and stays on, or never comes on at all, no DTCs set	Troubleshoot the MIL circuit.
Engine will not start (MIL works OK, no DTCs set, immobilizer indicator stays on or flashes)	Check for symptoms for the immobilizer system.
Engine starts but stalls immediately (MIL works OK, no DTCs set, immobilizer indicator stays on or flashes)	Check for symptoms for the immobilizer system.
Engine is hard to start (MIL works OK, no DTCs set)	1. 2. 3.	Test the battery. Bleed the fuel system. Test the fuel filter water level switch.	Low compression Intake air leaks Contaminated fuel
Cold fast idle too low (MIL works OK, no DTCs set)	1. 2. 3.	Check the idle speed. Bleed the fuel system. Test the fuel filter water level switch.
Cold fast idle too high (MIL works OK, no DTCs set)	1. 2.	Check the idle speed. Test the fuel filter water level switch.
Idle speed fluctuates (MIL works OK, no DTCs set)	1. 2. 3.	Check the idle speed. Bleed the fuel system. Test the fuel filter water level switch.	Intake vacuum leaks Contaminated fuel
After warming up, idle speed is above specifications without load (MIL works OK, no DTCs set)	Inspect APP sensor.
Fails emission test (MIL works OK, no DTCs set)	1. 2.	Without DPF system: Inspect the catalytic converter. With DPF system: Inspect the warm up catalytic converter.	Contaminated fuel Low compression Slipped/broken timing belt
Low power (MIL works OK, no DTCs set)	1. 2. 3.	Check the air cleaner element. Without DPF system: Inspect the catalytic converter. With DPF system: Inspect the warm up catalytic converter.	Contaminated fuel Low compression Camshaft timing Engine oil level
Engine stalls (MIL works OK, no DTCs set)	1. 2.	Bleed the fuel system. Check the idle speed.	Intake air leaks Faulty harness and sensor connections
Engine oil level indicator (amber) stays on or flashes (MIL works OK, no DTCs set)	Inspect the engine oil level sensor.
HDS does not communicate with the ECM or the vehicle	Troubleshoot the DLC circuit.
DPF REGENERATION REQUIRED display is on	Regenerate the DPF.
DPF CHECK SYSTEM display is on	1. 2. 3.	Regenerate the DPF. Check for damage or clogging at the DPF differential pressure sensor piping. Inspect the DPF.
SIL never comes on	Troubleshoot the shift indicator lamp.
When the clutch pedal pressed, light out of SIL is slow	Troubleshoot the shift indicator lamp.
SIL does not work once in a while	Troubleshoot the shift indicator lamp.
Shift up indicator lamp does not come on, or shift down indicator lamp does not come on	Check for body electrical system DTCs.
SIL stays on	Check for body electrical system DTCs.