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TROUBLESHOOTING MULTIPOINT FUEL INJECTION (MPI) 13A-49 YES : Go to Step 5. NO : Repair or replace the connector, or repair STEP 5. Check harness between engine coolant • Check earthing line for damage. Q: Is the check result normal? YES : Go to Step 6. NO : Repair or replace the connector, or repair STEP 6. M.U.T.-III data list • Item 6: Engine coolant temperature sensor OK: Engine cold state: At ambient temperature (atmospheric temperature) or equivalent. Engine hot state: At 80 − 120 °C Q: Is the check result normal? YES : Intermittent malfunction (Refer to GROUP 00 − How to Use Troubleshooting/Inspection Service Points − How to Cope with Intermittent Malfunctions NO : Replace the engine-ECU. Code No. P0131: Oxygen Sensor (front) Circuit Low Voltage OPERATION • The sensor signal is inputted to the engine-ECU connector terminal O2FL from the oxygen sensor • The oxygen sensor (front) connector terminal is earthed with engine-ECU connector terminal FUNCTION • The oxygen sensor (front) converts the concen- tration of oxygen in the exhaust emission into a • When the air-fuel ratio is richer than the theoreti- cal air-fuel ratio, the oxygen sensor (front) out- • In response to the signal, the engine-ECU con- trols the fuel injection amount so that the air-fuel TROUBLE JUDGMENT Check Conditions • More than 1 minute have passed since the engine starting sequence was completed. • Battery positive voltage is more than 11 V and is less than 16.5 V. • Oxygen sensor (front) offset voltage is more than 0.4 V and is less than 0.6 V. Judgement Criterion • Oxygen sensor (front) output voltage is less than 0.2 V for 2 seconds. FAIL-SAFE AND BACKUP FUNCTION • None PROBABLE CAUSES • Failed oxygen sensor (front) • Open/short circuit or harness damage in oxygen sensor (front) circuit or loose connector contact • Failed engine-ECU DIAGNOSIS PROCEDURE STEP 1. M.U.T.-III data list • Data list reference table (Refer to ). a. Item AC: Oxygen sensor (front) Q: Is the check result normal? YES : Intermittent malfunction (Refer to GROUP 00 − How to Use Troubleshooting/Inspection Service Points − How to Cope with Intermittent Malfunctions NO : Go to Step 2. STEP 2. Perform voltage measurement at oxygen • Disconnect connector, and measure at harness side. • Ignition switch: "ON" • Voltage between terminal engine-ECU OFLE line and body earth. OK: 0.4 − 0.6 V Q: Is the check result normal? YES : Go to Step 5. NO : Go to Step 3. |