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.
Diagnostic Procedure
- INSPECTION START
Which malfunction (A or B) is duplicated?
A or B
- A: GO TO 3.
- B: GO TO 2.
- CHECK INTAKE AIR LEAK
Check the following for connections.
- Air duct
- Vacuum hoses
- Intake air passage between air duct and intake manifold
OK or NG
- OK: GO TO 3.
- NG: Reconnect the parts.
- RETIGHTEN GROUND SCREWS
- Turn ignition switch OFF.
- Loosen and retighten engine ground screws.
- GO TO 4.
- CHECK MAF SENSOR POWER SUPPLY CIRCUIT
- Disconnect mass air flow (MAF) sensor harness connector.
- Turn ignition switch ON.
- Check voltage between MAF sensor terminal 2 and ground with CONSULT-II or tester.
Voltage: Battery voltage
OK or NG
- OK: GO TO 6.
- NG: GO TO 5.
- DETECT MALFUNCTIONING PART
Check the following.
- Harness for open or short between ECM relay and mass air flow sensor
- Harness for open or short between mass air flow sensor and ECM
- Repair harness or connectors.
- CHECK MAF SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
- Turn ignition switch OFF.
- Disconnect ECM harness connector.
- Disconnect TCM harness connector (A/T models).
- Check harness continuity between MAF sensor terminal 3 and ECM terminal 67, TCM terminal 42 (A/T models).
Refer to WIRING DIAGRAM .
Continuity should exist.
- Also check harness for short to ground and short to power.
OK or NG
- OK: GO TO 8.
- NG: GO TO 7.
- DETECT MALFUNCTIONING PART
Check the following.
- Harness for open or short between mass air flow sensor and ECM
- Harness for open or short between mass air flow sensor and TCM (A/T models)
- Repair open circuit or short to ground or short to power in harness or connectors.
- CHECK MAF SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
- Check harness continuity between MAF sensor terminal 4 and ECM terminal 51. Refer to WIRING DIAGRAM .
Continuity should exist.
- Also check harness for short to ground and short to power.
OK or NG
- OK: GO TO 9.
- NG: Repair open circuit or short to ground or short or short to power in harness or connectors.
- Check harness continuity between MAF sensor terminal 4 and ECM terminal 51. Refer to WIRING DIAGRAM .
- CHECK MASS AIR FLOW SENSOR
Refer to "COMPONENT INSPECTION ".
OK or NG
- OK: GO TO 10.
- NG: Replace mass air flow sensor.
- CHECK INTERMITTENT INCIDENT
Perform "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".
- INSPECTION END
Use the Manual With the Right Hardware
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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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