Inspection Procedures

CHECK HO2S AND ECM CONNECTORS
1. Check HO2S and ECM for poor connection, misplaced, bent, loose or corroded terminals.
Are both connectors good?

Yes: Go to next

No: Repair or replace it.
CHECK HO2S HEATER RESISTANCE
1. Turn ignition switch to OFF position and disconnect HO2S connector.
2. Measure resistance between terminals 3 and 4 of the HO2S connector.
Fig 1: Measuring Resistance Between Terminals 3 & 4 Of HO2S Connector
Courtesy of HYUNDAI MOTOR CO.
- 9ohm at 20°C ~ 24°C(68°F ~ 75.2°F)
  Is resistance within specification?
Yes: Go to next

No: Replace HO2S.
CHECK POWER TO HO2S HEATER
1. Turn ignition switch to ON position.
2. Measure voltage between terminal 3 of the HO2S harness connector and chassis ground.
Fig 2: Measuring Voltage Between Terminal 3 Of HO2S Harness Connector & Chassis Ground
Courtesy of HYUNDAI MOTOR CO.
- Specification: approximately B+
  Is voltage within specification?
Yes: Go to next

No: Repair open or short to ground in harness.
CHECK FOR SHORT TO POWER IN HARNESS
1. Turn ignition switch to OFF position.
2. Disconnect ECM and HO2S connectors.
3. Turn ignition switch to ON position.
4. Measure voltage between terminal 4 of the HO2S harness connector and chassis ground.
Fig 3: Measuring Voltage Between Terminal 4 Of HO2S Harness Connector & Chassis Ground
Courtesy of HYUNDAI MOTOR CO.
- Specification: below 0.5V
  Is voltage within specification?
Yes: Go to next

No: Repair short to power in harness.
CHECK FOR OPEN IN HARNESS
1. Turn ignition switch to OFF position.
2. Measure resistance between terminal 4 of the HO2S harness connector and 9 of the ECM harness connector.
Fig 4: Measuring Resistance Between Terminal 4 Of HO2S Harness Connector & 9 Of ECM Harness Connector
Courtesy of HYUNDAI MOTOR CO.
- Specification: below 1ohm
  Does resistance indicate continuity?
Yes: Proceed with ECM PROBLEM PROCEDURE .

No: Repair open in harness.