Fuel and Emissions Systems

Symptom Troubleshooting Index

11-5  

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. Test the battery, refer to the '01 Civic Shop Manual on this CD (see page 22-79).
  2. Test the starter, refer to the '01 Civic Shop Manual on this CD (see page 4-8).
  3. Troubleshoot the fuel pump circuit, refer to the '01 Civic Shop Manual on this CD (see page 11-127).
  • Low compression
  • Intake air leaks
  • Locked up engine
  • Slipped/ broken timing belt
  • 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 page 11-56).  
Engine will not start

(immobiliser indicator light comes on)

Troubleshoot the immobiliser system, refer to the '01 Civic Shop Manual on this CD (see page 22-245).  
Hard starting

(MIL works OK, no DTCs set)

  1. Test the battery, refer to the '01 Civic Shop Manual on this CD (see page 22-79).
  2. Check the fuel pressure, refer to the '01 Civic Shop Manual on this CD (see page 11-131).
  • Low compression
  • Intake air leaks
  • Contaminated fuel
Cold fast idle too low

(MIL works OK, no DTCs set)

Check the idle speed, refer to the '01 Civic Shop Manual on this CD (see page 11-125).  
Cold fast idle too high

(MIL works OK, no DTCs set)

  1. Check the idle speed (see page 11-71).
  2. Inspect/adjust the throttle cable, refer to the '01 Civic Shop Manual on this CD (see page 11-149).
  3. Inspect and test the throttle body, refer to the '01 Civic Shop Manual on this CD (see page 11-145).
 
Idle speed fluctuates

(MIL works OK, no DTCs set)

  1. Check the idle speed (see page 11-71).
  2. Inspect/adjust the throttle cable, refer to the '01 Civic Shop Manual on this CD (see page 11-149).
  3. Inspect and test the throttle body, refer to the '01 Civic Shop Manual on this CD (see page 11-145).
Intake air leaks
After warming up idle speed is below specifications with no load

(MIL works OK, no DTCs set)

  1. Troubleshoot the ALT FR signal circuit, refer to the '01 Civic Shop Manual on this CD (see page 11-120).
  2. Inspect and test the throttle body, refer to the '01 Civic Shop Manual on this CD (see page 11-145).
Vacuum hose clogged/cracked/poor connection
After warming up idle speed is above specifications with no load

(MIL works OK, no DTCs set)

Troubleshoot the ALT FR signal circuit, refer to the '01 Civic Shop Manual on this CD (see page 11-120).  
Low power

(MIL works OK, no DTCs set)

  1. Check the fuel pressure, refer to the '01 Civic Shop Manual on this CD (see page 11-131).
  2. Inspect and test the throttle body, refer to the '01 Civic Shop Manual on this CD (see page 11-145).
  3. Inspect/adjust the throttle cable, refer to the '01 Civic Shop Manual on this CD (see page 11-149).
Low compression
Engine stalls

(MIL works OK, no DTCs set)

  1. Check the fuel pressure, refer to the '01 Civic Shop Manual on this CD (see page 11-131).
  2. Check the idle speed (see page 11-71).
  3. Troubleshoot the brake pedal position switch signal circuit, refer to the '01 Civic Shop Manual on this CD (see page 11-123).
  • Intake air leaks
  • Faulty harness and sensor connections