Oxygen Sensor: Testing and Inspection

Engine Control System (Part 1 Of 7):

1999 Tiburon 2.0 L

1999 Elantra 2.0 L

CIRCUIT DIAGRAM

HARNESS INSPECTION PROCEDURE

SENSOR INSPECTION

NOTE
1. Before checking, warm up the engine until the engine coolant temperature reaches 80 to 95 °C (176 to 205 °F).
2. Use an accurate digital voltmeter.
Replace the oxygen sensor if there is a malfunction.

1. Disconnect the heated oxygen sensor connector, and measure the resistance between terminal 3 and terminal 4.

Standard Value
Temperature 400 °C Resistance 30 or more Ohms

2. Replace the oxygen sensor if there is a malfunction

Tightening Torque
Heated Oxygen Sensor 50 - 60 Nm (500 - 600 kg.cm, 37 - 44 lb.ft)

TROUBLESHOOTING PROCEDURES

TROUBLESHOOTING HINTS
When the lean/rich period is above 2.6 seconds in the condition that fully warm-up engine is 2,000 - 3,000 rpm and engine is above middle load.

TROUBLESHOOTING HINTS
1. If the heated oxygen sensor is defective abnormally, high emissions may occur.
2. If the heated oxygen sensor check has been normal, but the sensor output voltage is out of specification, check the following items related to the air fuel ratio control system.
- Faulty injector.
- Air leaks in the intake manifold.
- Faulty mass air flow sensor, EVAP valve and engine coolant temperature sensor.
- Wiring connection problem.
3. When 02 sensor output voltage is maintained as following for above 50 seconds.
- Upstream 0.4 V - 0.6 V
- Downstream : 0.4 V - 0.5 V

USING VOLTMETER

NOTE: If you release the accelerator pedal suddenly with the engine running about 4000 rpm, the fuel supply will be stopped for a while. When you suddenly press the accelerator pedal, the voltage will reach 'B' range. Then, when you let the engine idle again, the voltage fluctuates between 'A' and 'B' range. In this case, the O2 sensor can be determined as good.

AIR-FUEL CONTROL TROUBLESHOOTING PROCEDURE

TROUBLESHOOTING HINTS
Air/Fuel ratio stays rich or lean longer than specified period because of system malfunction.