DIAGNOSIS Required Special Tools: • MB991958: Scan Tool (MUT-III Sub Assembly) MB991824: V.C.I MB991827: USB Cable MB991911: Main Harness B • MB991316: Test Harness

STEP 1. Using scan tool MB991958, check data list item 59: Heated Oxygen Sensor Bank 2, Sensor 2 (left rear).

To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. (1) Connect scan tool MB991958 to the data link connector. (2) Start the engine and run at idle. (3) Set scan tool MB991958 to the data reading mode for item 59, Heated Oxygen Sensor Bank 2, Sensor 2 (left rear). • Warm up the engine. When the engine is revved, the output voltage should repeat 0 volt and 0.6 to 1.0 volt alternately. (4) Turn the ignition switch to the "LOCK" (OFF) position. Q: Is the sensor operating properly? YES: Go to Step 2. NO: Refer to DTC P0156 - Heated Oxygen Sensor Circuit (bank 2, sensor 2) , DTC P0157 - Heated Oxygen Sensor Circuit Low Voltage (bank 2, sensor 2) , DTC P0158-Heated Oxygen Sensor Circuit High Voltage (bank 2, sensor 2) , DTC P0159 - Heated Oxygen Sensor Circuit Slow Response (bank 2, sensor 2) .

STEP 2. Check for exhaust leaks. Q: Are there any abnormalities? YES: Repair it. Then go to Step 14. NO: Go to Step 3.

STEP 3. Check for intake system vacuum leaks. Q: Are there any abnormalities? YES: Go to Step 4. NO: Repair it. Then go to Step 14.

STEP 4. Check connector A-09 at the left bank heated oxygen sensor (front) for damage.

Q: Is the connector in good condition? YES: Go to Step 5. NO: Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 14.

STEP 5. Check the left bank heated oxygen sensor (front).

(1) Disconnect the left bank heated oxygen sensor (front) connector A-09 and connect test harness special tool, MB991316 to the connector on the left bank heated oxygen sensor (front) side. (2) Warm up the engine until engine coolant 80°C (176°F) or higher.

(3) Perform a tracing for 5 minutes or more with the engine speed of 4,500 r/min. (4) Connect a digital volt meter between terminal No. 2 (black clip) and terminal No. 4 (white clip). (5) While repeatedly revving the engine, measure the left bank heated oxygen sensor (front) output voltage. Standard value: 0.6 - 1.0 volt • Be very careful when connecting the jumper wire; incorrect connection can damage the oxygen sensor. • Be careful the heater is broken when voltage of beyond 8 volts is applied to the oxygen sensor heater. NOTE: If the sufficiently high temperature (of approximate 400°C or more) is not reached although the oxygen sensor is normal, the output voltage would be possibly low although the rich air-fuel ratio. Therefore, if the output voltage is low, use a jumper wire to connect the terminal No.1 (red clip of special tool) and the terminal No. 3 (blue clip of special tool) of the oxygen sensor with a (+) terminal and (-) terminal of 8 volts power supply respectively, then check again. Q: Is the voltage between 0.6 and 1.0 volt? YES: Go to Step 6. NO: Replace the left bank heated oxygen sensor (front). Then go to Step 14.

STEP 6. Check connector A-04 at injector intermediate connector for damage.

Q: Is the connector in good condition? YES: Go to Step 7. NO: Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 14.

STEP 7. Check the left bank injector resistance at intermediate connector A-04.

(1) Disconnect the injector intermediate connector A-04.

(2) Measure the resistance between each injector side connector terminal. a.Measure the resistance between terminal No. 2 and No. 8 when measuring No. 2 cylinder. b.Measure the resistance between terminal No. 7 and No. 8 when measuring No. 4 cylinder. c.Measure the resistance between terminal No. 5 and No. 8 when measuring No. 6 cylinder. • Resistance should be between 13 and 16 ohms [at 20°C (68°F)]. Q: Is the measured resistance between 13 and 16 ohms [at 20°C (68°F)]? YES: Go to Step 10. NO: Go to Step 8.

STEP 8. Check connector A-70, A-71, A-72 at left bank injector for damage.

(1) Remove the intake manifold. (2) Check the left bank injector connector, which deviates from the standard value at Step 7. Q: Is the connector in good condition? YES: Go to Step 9. NO: Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 14.

STEP 9. Check the left bank injector.

(1) Check the left bank injector connector, which deviates from the standard value at Step 7.

(2) Measure the resistance between injector side connector terminal No. 1 and No. 2. Standard value: 13 - 16 ohms [at 20°C (68°F)] Q: Is the resistance between 13 and 16 ohms [at 20°C (68°F)]? YES: Repair harness wire between injector intermediate connector and left bank injector connector because of harness damage. Then go to Step 14. NO: Replace the injector. Then go to Step 14.

STEP 10. Check connector C-90, C-91 at PCM for damage.

Q: Is the connector in good condition? YES: Go to Step 11. NO: Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 14.

STEP 11. Check for harness damage between left bank heated oxygen sensor (front) connector A-09 (terminal No. 4) and PCM connector C-91 (terminal No. 71).

Q: Is the harness wire in good condition? YES: Go to Step 12. NO: Repair it. Then go to Step 14.

STEP 12. Check for harness damage between left bank injector connector and PCM connector.

a.Check the harness wire between left bank injector connector A-72 (terminal No. 2) and PCM connector C-89 (terminal No. 9) when checking No. 2 cylinder. b.Check the harness wire between left bank injector connector A-71 (terminal No. 2) and PCM connector C-89 (terminal No. 2) when checking No. 4 cylinder. c.Check the harness wire between left bank injector connector A-70 (terminal No. 2) and PCM connector C-89 (terminal No. 25) when checking No. 6 cylinder. Q: Is the harness wire in good condition? YES: Go to Step 13. NO: Repair it. Then go to Step 14.

STEP 13. Check the fuel pressure. Refer to On - Vehicle Service - Fuel Pressure Test . Q: Is the fuel pressure normal? YES: Replace the PCM. Then go to Step 14. NO: Repair it. Then go to Step 14.