DTC P0138 O2 SENSOR CIRCUIT HIGH VOLTAGE (BANK 1 SENSOR 2)

DTC P0138 O 2 SENSOR CIRCUIT HIGH VOLTAGE (BANK 1 SENSOR 2)

(1)	Atmosphere	(A)	Electromotive force
(2)	Exhaust	(B)	Air fuel ratio
(3)	Electromotive force	(C)	Rich
		(D)	Lean
		(E)	Theoretical air fuel ratio
		(F)	Comparative voltage

ENABLE CONDITION (USED ONLY FOR MALFUNCTION JUDGMENT)

Secondary Parameters	Enable Conditions
Closed loop control with rear oxygen sensor	In operation
Target output voltage of rear oxygen sensor	≥ 0.54 V
Amount of intake air	≥ 10 g/s
Engine coolant temperature	≥ 75°C (167°F)
Misfire detection during 200 engine revs.	< 5 times
Compensation factor for front oxygen (A/F) sensor	Not in limit value
Battery voltage	> 10.9 V
5 seconds or more fuel shut-off in decel.	Experienced

GENERAL DRIVING CYCLE

Perform the diagnosis once after starting the engine.

DIAGNOSTIC METHOD

Abnormality Judgment

Judge NG when the malfunction criteria below are completed.

Judgment Value

Malfunction Criteria	Threshold Value
Min. output voltage	> 250 mV

Time Needed for Diagnosis: 200 seconds

Malfunction Indicator Light Illumination: Detect when malfunction occurs in 2 continuous driving cycles.

Normality Judgment

Judge OK when the malfunction criteria below are completed.

Judgment Value

Malfunction Criteria	Threshold Value
High side diagnosis of rear oxygen sensor voltage	Incomplete
Min. output voltage	≤ 250 mV

DTC CLEAR CONDITION

•	When the OK idling cycle was completed 40 times in a row

•	When “Clear Memory” was performed

MALFUNCTION INDICATOR LIGHT CLEAR CONDITION

•	When the OK driving cycle was completed 3 times in a row

•	When “Clear Memory” was performed

FAIL SAFE

Sub feedback control: Not allowed

ECM OPERATING AT DTC SETTING

Memorize the freeze frame data. (For test mode $02)