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HOMESERVICE MANUALSHONDA2008CIVIC SI, 4D SEDANREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 88 (FUEL SYSTEM & EMISSIONS SYSTEM (R18A1 ENGINE))SYMPTOM TROUBLESHOOTING INDEX
2008 Honda Civic Si, 4D Sedan

Symptom Troubleshooting Index

2008 Honda Civic Si, 4D SedanSECTION Symptom Troubleshooting Index
WARNING: This page is about a different variant/trim than selected.

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 TROUBLESHOOTING INDEX

Symptom Diagnostic procedure Also check for
Engine will not start (MIL works OK, no DTCs set)
  1. Test the battery (see BATTERY TEST ).
  2. Test the starter:
    • M/T model (see M/T )
    • A/T model (see A/T )
  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
  • 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 MIL circuit (see MIL CIRCUIT TROUBLESHOOTING ).  
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.  
Engine starts but stalls immediately (MIL works OK, no DTCs set, immobilizer indicator stays on or flashes) Check the immobilizer system.  
Engine is hard to start (MIL works OK, no DTCs set)
  1. Test the battery (see BATTERY TEST ).
  2. Check the fuel pressure (see FUEL PRESSURE TEST ).
  3. Clean the throttle body (see THROTTLE BODY CLEANING ).
  • Low compression
  • Intake air leaks
  • Contaminated fuel
  • Weak spark
Cold fast idle too low (MIL works OK, no DTCs set)
  1. Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
  2. Check the idle speed (see IDLE SPEED INSPECTION ).
  3. Clean the throttle body (see THROTTLE BODY CLEANING ).
  
Cold fast idle too high (MIL works OK, no DTCs set)
  1. Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
  2. Check the idle speed (see IDLE SPEED INSPECTION ).
  3. Do the throttle position learning check (see THROTTLE BODY TEST ).
  
Idle speed fluctuates (MIL works OK, no DTCs set)
  1. Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
  2. Check the idle speed (see IDLE SPEED INSPECTION ).
  3. Do the carbon accumulation check (see THROTTLE BODY TEST ).
 Intake vacuum leaks
After warming up, idle speed is below specification without load (MIL works OK, no DTCs set)
  1. Troubleshoot the alternator FR signal circuit (see ALTERNATOR FR SIGNAL CIRCUIT TROUBLESHOOTING ).
  2. Do the carbon accumulation check (see THROTTLE BODY TEST ).
  3. Troubleshoot the A/C signal switch circuit (see A/C SIGNAL CIRCUIT TROUBLESHOOTING ).
  
After warming up, idle speed is above specification without load (MIL works OK, no DTCs set)
  1. Troubleshoot the alternator FR signal circuit (see ALTERNATOR FR SIGNAL CIRCUIT TROUBLESHOOTING ).
  2. Inspect the APP sensor (see APP SENSOR SIGNAL INSPECTION ).
  3. Troubleshoot the A/C signal switch circuit (see A/C SIGNAL CIRCUIT TROUBLESHOOTING ).
  
After warming up, idle speed drops when steering wheel is turning (MIL works OK, no DTCs set)
  1. Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
  2. Troubleshoot the PSP switch signal circuit (see PSP SWITCH SIGNAL CIRCUIT TROUBLESHOOTING ).
  3. Do the carbon accumulation check (see THROTTLE BODY TEST ).
 Power steering system
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
Engine stalls (MIL works OK, no DTCs set)
  1. Do the ECM/PCM idle learn procedure (see ECM/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
Difficult to refuel (MIL works OK, no DTCs set)
  1. Check the fuel vent tube between the EVAP canister and the fuel tank.
  2. Check the fuel tank vapor recirculation tube between the fuel pipe and the fuel tank.
  3. Replace the fuel tank unit (see FUEL TANK UNIT REMOVAL/INSTALLATION ).
  4. Replace the fuel tank (see FUEL TANK REPLACEMENT ).
 Malfunctioning gas station filling nozzle.
Fuel overflows during refueling (No DTCs set)
  1. Replace the fuel tank unit (see FUEL TANK UNIT REMOVAL/INSTALLATION ).
  2. Replace the fuel tank (see FUEL TANK REPLACEMENT ).
 Malfunctioning gas station filling nozzle.
HDS does not communicate with the ECM/PCM or the vehicle Troubleshoot the DLC circuit (see DLC CIRCUIT TROUBLESHOOTING ).  
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.