Hyundai Diagnostic (HDS) Testing Procedure

The front and rear oxygen sensor signals can be monitored using HDS. The sensor signals can be observed using either "Custom Meters" or "Signal Wave Forms" on the HDS machine. The "Signal Wave Forms" procedure should be used since the signal resolution is better with the engine at 2500 rpm, which is required for proper testing.

NOTE:
When HDS is used to monitor oxygen sensor signals on 1996 MY and later Accent, Elantra and Tiburon vehicles, a 0.70 V signal offset is observed. This shifts the sensor readings 0.70 V higher so the new signal range is 0.70 V to 1.70 V. This shift is seen only when using the HDS machine because the sensor signal is read before it is processed (filtered) by the PCM. The offset has no effect on the sensor signal appearance or frequency. (See graph.)

1. Connect the scan tool and retrieve all diagnostic codes (see Scan Tool Testing Procedure section for details). If codes other than oxygen sensor codes are present, diagnose/repair these conditions BEFORE continuing with oxygen sensor diagnosis.

2. Connect HDS to vehicle.

3. Warm up vehicle to operating temperature (until the engine cooling fan begins to cycle, approximately 3 minutes).





4. Select "Signal Wave Forms" from HDS.





5. Select the front and rear oxygen sensor signals and the throttle position sensor (TPS) signal (the TPS is used to establish an approximate relationship between the throttle position and engine rpm).





6. Select "Digital Record" from the "Options" menu.





7. Select CTRL and set ms/div to 30.00. Click "OK".

8. Select "Run". Run the vehicle at 2500 rpm for several minutes, watch the signal. Record the signal after the engine has stabilized at 2500 rpm. The front oxygen sensor signal should fluctuate quickly (Sonata from 0 to 1.0 V, Accent Elantra & Tiburon from 0.70 to 1.70 V).





9. To view recorded data select 'Options" and 'Data Play Back" and the screen will show the analog form of the recorded data. To use the Digital Overlay Feature during playback select "CTRL", "Playback", "Digital". Select "Zoom" and "-64" to change the scale to get the 1.92 Sec/Div resolution.





10. The front sensor should cross the midpoint of signal travel at least 7 times in 5 seconds when the vehicle is at 2500 rpm. The rear oxygen sensor should change slowly, if at all.

11. Record the sensors' reaction to a fuel cut by revving engine to 4000 rpm and let it stabilize. Quickly close the throttle and observe the front and rear sensor signals (see plots 2 & 5).

Note:
A vacuum leak can also be intentionally created to check sensor response (see plots 3 & 4).

12. If an intermittent condition is reported, "wiggle check" all the connectors and wiring harnesses related to the oxygen sensor while the vehicle and the HDS are running.