Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Fuel Injector Circuit
- Check or repair only faulty parts.
- After servicing or replacing faulty parts, perform Clear Memory Mode Ref. to ENGINE (DIAGNOSTICS) (EXCEPT FOR STI)>Clear Memory Mode>OPERATION , and inspection mode Ref. to ENGINE (DIAGNOSTICS) (EXCEPT FOR STI)>Inspection Mode>PROCEDURE .
- Use the check board when measuring the ECM terminal voltage and resistance.
Wiring diagram:
Engine Electrical System Ref. to WIRING SYSTEM>Engine Electrical System>WIRING DIAGRAM .
- CHECK OPERATION OF EACH FUEL INJECTOR
.
While cranking the engine, check each fuel injector emits operating sound. Use a sound scope or listen by attaching a screwdriver to the injector for this check.
Does the fuel injector emit operating sound?
Yes: Check the fuel pressure. Ref. to MECHANICAL(EXCEPT FOR STI)>Fuel Pressure>INSPECTION .
No: Go to 2
- CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR CONNECTOR
.
- Turn the ignition switch to OFF.
- Disconnect the connector from ECM.
- Measure the resistance of harness between ECM connector and fuel injector connector.
Connector & terminal
#1 (E158) No. 12 - (E5) No. 1:
#1 (E158) No. 11 - (E5) No. 2:
#2 (E158) No. 24 - (E16) No. 1:
#2 (E158) No. 23 - (E16) No. 2:
#3 (E158) No. 36 - (E6) No. 1:
#3 (E158) No. 35 - (E6) No. 2:
#4 (E158) No. 48 - (E17) No. 1:
#4 (E158) No. 47 - (E17) No. 2:
Is the resistance less than 1 Ω?
Yes: Go to 3
No: Repair the open circuit of the harness between the ECM connector and fuel injector connector.
- CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR CONNECTOR
.
Measure the resistance of harness between ECM connector and chassis ground.
Connector & terminal
#1 (E158) No. 12 - Chassis ground:
#1 (E158) No. 11 - Chassis ground:
#2 (E158) No. 24 - Chassis ground:
#2 (E158) No. 23 - Chassis ground:
#3 (E158) No. 36 - Chassis ground:
#3 (E158) No. 35 - Chassis ground:
#4 (E158) No. 48 - Chassis ground:
#4 (E158) No. 47 - Chassis ground:
Is the resistance 1 MΩ or more?
Yes: Go to 4
No: Repair the short circuit to ground in harness between ECM connector and fuel injector connector.
- CHECK EACH FUEL INJECTOR
.
Check each fuel injector. Ref. to FUEL INJECTION (FUEL SYSTEMS) (EXCEPT FOR STI)>Fuel Injector>INSPECTION .
Is the check result OK?
Yes: Go to 5
No: Replace the faulty fuel injector. Ref. to FUEL INJECTION (FUEL SYSTEMS) (EXCEPT FOR STI)>Fuel Injector .
- CHECK FOR POOR CONTACT
.
Check for poor contact of ECM connector.
Is there poor contact of ECM connector?
Yes: Repair the poor contact of ECM connector.
No: Inspection using "General Diagnostic Table". Ref. to ENGINE (DIAGNOSTICS) (EXCEPT FOR STI)>General Diagnostic Table>INSPECTION .
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.
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