The downstream heated oxygen sensor (HO2S) is forced rich and lean and monitored by the ECM/PCM. This DTC sets when the ECM/PCM does not detect the output of the HO2S in a calibrated amount of time.
Item | Detecting Condition | Possible Cause |
DTC Strategy |
•
Downstream O2 sensor signal too low | 1. Poor connection 2. Open or Short to ground in harness 3. HO2S(S1/S2) 4. ECM/PCM 5. Exhaust leaks |
Enable Conditions |
•
no fuel cut off
•
no full load
•
no catalyst overheating protection
•
11V < Battery voltage < 16V | |
Threshold Value |
•
Downstream O2 sensor voltage < 0.75V when lambda set point = 0.8 | |
Diagnostic Time |
•
7 sec lambda set point shift to corresponding side | |
MIL On Condition |
•
2 driving cycles |
※ S1 : upstream oxygen sensor / S2 : downstream oxygen sensor
