Component Inspection

Visually/physically inspect following items:
1. Inspect the front HO2S for any silicon contamination. This contamination will be indicated by a white powdery coating and this will result in a but false voltage signal.
2. If contamination is evident on the HO2S, replace contaminated sensor and go to next step.
Warm up the engine to normal operating temperature and check that HO2S signal is active.
Connect scan tool and monitor the "O2 SNSR VOLT.(B1/S1)" parameter on the scan tool data list.
Test Condition: Engine "ON" & In Closed loop mode

Fig 1: O2 Sensor Voltage Signals (Acceleration)
Courtesy of KIA MOTORS AMERICA, INC.
- Signal decreases with rich air/fuel mixture and increases with lean air/fuel mixture
- Fuel cut-off mode (PCM will stop the fuel supply when release the accelerator pedal suddenly after engine running about 4000rpm): approx. 3.2V
Fig 2: O2 Sensor Voltage Signals (Deceleration)
Courtesy of KIA MOTORS AMERICA, INC.

Fig 3: O2 Sensor Voltage Signals (Fuel Cut-Off Mode)
Courtesy of KIA MOTORS AMERICA, INC.

A: Acceleration, B: Deceleration; C: Fuel Cut-off mode
Is sensor data near the specified value?
YES
- Check for poor connection between PCM and component: backed out terminal, improper mating, broken locks or poor terminal to wire connection. Repair as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure.
NO
- Substitute with a known-good HO2S and check for proper operation. If the problem is corrected, replace HO2S and then go to "VERIFICATION OF VEHICLE REPAIR " procedure