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Symptom Troubleshooting Index

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, IMA motor works OK)
  1. Test the 12 volt battery (see 12 VOLT BATTERY TEST ).
  2. Test the starter (see STARTER PERFORMANCE TEST ).
  3. Check the fuel pressure (see FUEL PRESSURE TEST ).
  4. Troubleshoot the fuel pump circuit (see FUEL PUMP CIRCUIT TROUBLESHOOTING ).
  • Low compression
  • No ignition spark
  • Intake air leaks
  • Restricted exhaust system
  • Locked up engine
  • Broken cam chain
  • Fuel contamination
Engine will not start (MIL comes on and stays on, no DTCs set, starter or IMA motor works OK) Troubleshoot the DLC circuit (see DLC CIRCUIT TROUBLESHOOTING ).
  • Low compression
  • No ignition spark
  • Intake air leaks
  • Locked up engine
  • Broken cam chain
  • Fuel contamination
  • No power to PCM
  • No ground to PCM
  • Short in reference voltage circuit
MIL comes on and stays on, or never comes on at all, no DTCs set Troubleshoot the MIL circuit (see MIL CIRCUIT TROUBLESHOOTING ).  
Engine will not start (MIL works OK, no DTCs set, immobilizer indicator stays on or flashes) Check the immobilizer system (see SYSTEM CHECK ).  
Engine starts but stalls immediately (MIL works OK, no DTCs set, immobilizer indicator stays on or flashes) Check the immobilizer system (see SYSTEM CHECK ).
  • Low compression
  • Intake air leak
  • Weak spark
  • Low fuel pressure
Engine is hard to start (MIL works OK, no DTCs set)
  1. Test the 12 volt battery (see 12 VOLT BATTERY TEST ).
  2. Check the fuel pressure (see FUEL PRESSURE TEST ).
  3. Clean the throttle body (see THROTTLE BODY TEST ).
  • Low compression
  • Intake air leaks
  • Fuel contamination
  • Weak spark
Cold fast idle too low (MIL works OK, no DTCs set)
  1. Do the PCM idle learn procedure (see PCM IDLE LEARN PROCEDURE ).
  2. Check the idle speed (see IDLE SPEED INSPECTION ).
  3. Clean the throttle body (see THROTTLE BODY TEST ).
  • Incorrect valve adjustment
  • Fuel contamination
Cold fast idle too high (MIL works OK, no DTCs set)
  1. Do the PCM idle learn procedure (see PCM IDLE LEARN PROCEDURE ).
  2. Check the idle speed (see IDLE SPEED INSPECTION ).
  • Intake air leak
  • Incorrect valve adjustment
Idle speed fluctuates (MIL works OK, no DTCs set)
  1. Do the PCM idle learn procedure (see PCM IDLE LEARN PROCEDURE ).
  2. Check the idle speed (see IDLE SPEED INSPECTION ).
  3. Do the carbon accumulation check (see THROTTLE BODY TEST ).
  4. Troubleshoot the A/C signal circuit (see A/C SIGNAL CIRCUIT TROUBLESHOOTING ).
  • Incorrect valve timing or clearance adjustment
  • Intake air leaks
After warming up, idle speed is below specifications without load (MIL works OK, no DTCs set) Do the carbon accumulation check (see THROTTLE BODY TEST ).  
After warming up, idle speed is above specifications without load (MIL works OK, no DTCs set) Inspect the APP sensor (see APP SENSOR SIGNAL INSPECTION ).  
Low power (MIL works OK, no DTCs set) Check the fuel pressure (see FUEL PRESSURE TEST ).
  • Low compression
  • Incorrect camshaft timing
  • Incorrect engine oil level
  • Exhaust restriction
  • Fuel contamination
Engine stalls (MIL works OK, no DTCs set)
  1. Do the PCM idle learn procedure (see PCM IDLE LEARN PROCEDURE ).
  2. Check the fuel pressure (see FUEL PRESSURE TEST ).
  3. Check the idle speed (see IDLE SPEED INSPECTION ).
  4. Troubleshoot the brake pedal position switch signal circuit (see BRAKE PEDAL POSITION SWITCH SIGNAL CIRCUIT TROUBLESHOOTING ).
  • Intake air leaks
  • Faulty harness and sensor connections
  • Fuel contamination
Difficult to refuel (MIL works OK, no DTCs set)
  1. Check the fuel tank vapor control valve hose between the EVAP canister and the fuel tank.
  2. Inspect the fuel filler neck for restrictions.
  3. Replace the fuel tank unit (see FUEL TANK UNIT REMOVAL AND INSTALLATION ).
  4. Replace the fuel tank (see FUEL TANK REPLACEMENT ).
  • Malfunctioning gas station filling nozzle
  • Faulty fuel tank vapor control valve
Fuel cap warning message stays on (MIL works OK, no DTCs set) Troubleshoot the fuel cap warning message system (see DTC P145C: EVAP SYSTEM PURGE FLOW MALFUNCTION )  
HDS does not communicate with the PCM or the vehicle Troubleshoot the DLC circuit (see DLC CIRCUIT TROUBLESHOOTING ).  
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