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TROUBLESHOOTING MULTIPORT FUEL INJECTION (MPI) 13A-51 FUNCTION • The engine-ECU <M/T> or engine-A/T-ECU <A/T> effects air-fuel ratio feedback control in • If the oxygen sensor (front) has deteriorated, corrections will be made by the oxygen sensor • Diagnosis code P0125 becomes stored in memory if a failure is detected in the above TROUBLE JUDGMENT Check Conditions • The engine coolant temperature approximately 76 °C or more. • Within the range of air-fuel ratio feedback operation. • Not in low speed operation. Judgment Criterion • The oxygen sensor output voltage is not deviated from 0.5 V for 30 seconds. PROBABLE CAUSE • Failed oxygen sensor (front) • Harness damage in oxygen sensor (front) circuit or loose connector contact • Failed oxygen sensor (rear) NOTE: When the oxygen sensor (front) begins to • Failed fuel system • Failed exhaust system • Failed engine-ECU <M/T> • Failed engine-A/T-ECU <A/T> DIAGNOSIS PROCEDURE STEP 1. MUT-III diagnosis code Q: Is any other diagnosis code than P0170 or P0173 output? YES : Inspection chart for diagnosis code (Refer to NO : Go to Step 2 . STEP 2.MUT-III data list • Refer to Data List Reference Table a. Item 12: Air flow sensor c. Item 59: Cylinder 1, 4 oxygen sensor (front) d. Item 69: Cylinder 2, 3 oxygen sensor (rear) Q: Are the check results normal? YES : Go to Step 3 . NO : Perform the diagnosis code classified check STEP 3: MUT-III data list • Refer to Data List Reference Table a. Item 25: Barometric pressure sensor Q: Are the check results normal? YES : Go to Step 4 . NO : Replace engine-ECU <M/T> or STEP 4.Check for intake of air from intake hose Q: Is the check result normal? YES : Go to Step 5 . NO : Repair. STEP 5.Check for leakage of exhaust emission Q: Is the check result normal? YES : Go to Step 6 . NO : Repair. STEP 6.Check throttle body (throttle valve Q: Is the check result normal? YES : Go to Step 7 . NO : Clean throttle body (throttle valve portion) ). |