The heated oxygen sensor (HO2S) monitor tracks the rate of voltage change during the rise and fall of the HO2S signal. When the rate of voltage change is less than a calibrated value, the PCM begins to modify the fuel trim attempting to increase the HO2S voltage switch rate. This DTC sets when the PCM is at the allowable limit or has exceeded an allowable length of time for fuel trim modification, without etecting an acceptable rate of voltage change.
Item | Detecting Condition | Possible Cause | |
Case 1 | DTC Strategy |
•
Transient time monitor(Rich to Lean) * HMC Remark : Catalyst monitoring is done by Rich to Lean step only | 1. Poor connection 2. B1S2 3. ECM |
Enable Conditions |
•
B+ > 11.0 V
•
1200 rpm < Engine speed < 3520 rpm
•
EGT around downstream O2S > 425 ℃(797 °F)
•
Intergrated Exhaust gas mass flow > 0.2 kg/h
•
Exhaust gas mass flow > 10 kg/h
•
-15 kg/h < Delta Exhaust gas mass flow < 15 kg/h
•
Fuel system status : Fuel cut off
•
Downstream O2S voltage before fuel cut > 0.63 V | ||
Threshold Value |
•
Transient time(average): Minimum duration(1/Max gradient) of downstream O2S voltage from 0.63V to 0.25V during fuel cut off > 0.30 sec(3 times per driving) | ||
Diagnostic Time |
•
3 valid fuel cut-off phases | ||
Case 2 | DTC Strategy |
•
Response time monitor (Rich to Lean) error will be stored immediately when exceeding the threshold once(3times monitoring) | |
Enable Conditions |
•
B+ > 11.0 V
•
1200 rpm < Engine speed < 3520 rpm
•
EGT around downstream O2S > 425 ℃(797 °F)
•
Intergrated Exhaust gas mass flow > 0.2 kg/h
•
Exhaust gas mass flow > 10 kg/h
•
-15 kg/h < Delta Exhaust gas mass flow < 15 kg/h
•
Fuel system status : Fuel cut off
•
Downstream O2S voltage before fuel cut > 0.63 V | ||
Threshold Value |
•
Response time OSC integration of catalyst When downstream O2S voltage from 0.63V to 0.25V during fuel cut off > Exh.gas mass flow | ||
Diagnostic Time |
•
3 valid fuel cut-off phases | ||
Case 3 | DTC Strategy |
•
Transient time monitor(Lean to Rich) | |
Enable Conditions |
•
B+ > 11.0 V
•
1200 rpm < Engine speed < 3520 rpm
•
1200 rpm < Engine speed < 3520 rpm
•
Intergrated Exhaust gas mass flow > 0.2 kg/h
•
Exhaust gas mass flow > 8 kg/h
•
-30 kg/h < Delta Exhaust gas mass flow < 50 kg/h
•
Fuel system status : after a fuel cut off
•
Downstream O2S voltage before fuel cut > 0.15 V | ||
Threshold Value |
•
Transient time(average): Minimum duration(1/Max gradient) of downstream O2S voltage from 0.25V to 0.63V after fuel cut in > 0.45 sec(3 times per driving) | ||
Diagnostic Time |
•
3 valid oxygen purge phases after fuel cut-off | ||
Case 4 | DTC Strategy |
•
Response time monitor (Lean to Rich) error will be stored immediately when exceeding the threshold once(3times monitoring) | |
Enable Conditions |
•
B+ > 11.0 V
•
1200 rpm < Engine speed < 3520 rpm
•
EGT around downstream O2S > 425 ℃(797 °F)
•
Intergrated Exhaust gas mass flow > 0.2 kg/h
•
Exhaust gas mass flow > 8 kg/h
•
-30 kg/h < Delta Exhaust gas mass flow < 50 kg/h
•
Fuel system status : after a fuel cut off
•
Downstream O2S voltage before fuel cut > 0.15 V | ||
Threshold Value |
•
Response time OSC integration of catalyst When downstream O2S voltage from 0.25V to 0.63V after fuel cut in > Exh.gas mass flow | ||
Diagnostic Time |
•
3 valid oxygen purge phases after fuel cut-off | ||
MIL ON Condition |
•
2 driving cycles | ||
※ S1 : upstream oxygen sensor / S2 : downstream oxygen sensor
