Code 59

Oxygen Sensor Circuit:

To test the Oxygen Sensor, located in the rear exhaust manifold after the turbo charger, proceed as follows.

O2 SENSOR TEST
1. Start and warm the engine until the coolant temperature exceeds 80~C (176~F).
2. Connect a volt meter with at least 10 megaohm resistance to sensor terminal A1 (do not disconnect the connector).
3. Accelerate the engine in second gear (M/T) or L range (A/T) to 3500 rpm at wide open throttle.

Voltage:
Approximately 600 - 1,000 mV.

4. Faulty results in the above test may be caused by:
a. Engine mechanical problems
b. Open or shorted wiring harness
c. Fuel pressure
d. Fuel mixture
5. Perform all tests before replacing the sensor.

O2 SENSOR HEATER TEST
1. Test heater function at cold engine temperatures
2. Disconnect the O2 sensor connector.
3. Using an ohm meter, check for continuity between O2 sensor connector terminals 3 and 4.

Continuity:
Should exist

4. Connect a volt meter to oxygen harness connector terminal 1.
5. Start engine and measure voltage at idle.

Voltage:
System Voltage.

NOTE: After warm-up, No voltage will be present.


5. Raise engine speed to 5000 RPM and measure voltage.

Voltage:
0 Volts.

Osciloscope Test:

OSCILLOSCOPE TEST
1. Connect scope pickup probe to the sensor terminal 1.
2. Warm engine to operating temperature and keep it running at 2,000 RPM, check the waveform on the scope. If scope pattern is not as depicted in image, the sensor may be bad or there could be a fuel mixture problem. Refer to DIAGNOSIS BY SYMPTOM for further system troubleshooting before replacing the assembly.

HARNESS TEST
1. Disconnect the oxygen sensor and the ECU connectors.

2. Using an Ohmmeter, check for continuity between the ECU harness connector terminal 7 and the oxygen sensor harness connector terminal 1.

Continuity:
Should exist.

3. Using an Ohmmeter, check for continuity (short) to ground between the ECU harness connector terminal 7 and the oxygen sensor harness connector terminal 1.

Continuity:
Should not exist.

4. Using an Ohmmeter, check for continuity between the ECU harness connector terminal 12 and the oxygen sensor harness connector terminal 2.

Continuity:
Should exist.

5. Using an Ohmmeter, check for continuity between the oxygen sensor harness connector terminal 4 and ground.

Continuity:
Should exist.

If any of the previous tests produce unsatisfactory results, the harness will need to be repaired or replaced. Once repairs have been completed, clear the trouble codes and road test the vehicle to confirm that the repair has corrected the problem and the code doesn't return.

If the same trouble code reoccurs, it is possible that there is an intermittent failure of the component or the ECU. Check for looseness at all harness junctions and test for an intermittent failure.