Fuel System > Engine Control System > P0134 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)

Component Location

General Description

In order to control emissions of the CO, HC and NOx components of the exhaust gas, heated oxygen sensor (HO2S), mounted on the front side and rear side of catalytic converter, detects the oxygen content in the exhaust gas. The front HO2S signal is used to control air/fuel ratio (closed loop fuel control) and the rear HO2S signal is used to monitor front HO2S and catalyst for proper operation.

The HO2S requires a minimum temperature to operate properly and provide a closed loop fuel control system. The HO2S contains the heater element to reduce its warming-up time and ensure its performance during all driving conditions.

The oxygen sensor generates a voltage that indicates the difference between the oxygen content of the exhaust stream and the oxygen content of ambient air. When the exhaust stream is “rich,” there is more oxygen in the ambient air than in the exhaust stream, so the voltage will be higher.

DTC Description

Checking output signals from HO2S under detecting condition, if an output voltage is approx.0.45V or 3.5V for more than predetermined time, PCM sets P0134. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.

DTC Detecting Condition

Item

Detecting Condition

Possible cause

DTC Strategy

•	Monitor signal voltage

•	Poor connection

•	Open in harness

•	HO2S(B1/S1)

•

PCM

Enable Conditions

•	Battery voltage ≥ 10V

•	Engine running ≥ 60 sec.

•	Engine warm-up state

•	No disable faults

Thresh old value

Case 1

•	1.2V ≤ Voltage of HO2S ≤ 3.9V (at pumping current ON)

Case 2

•	0.415V ≤ Voltage of HO2S ≤ 0.515V (at pumping current OFF)

Diagnosis Time

•	Continuous (more than 76.5 sec.failure for every 90 sec.test)

MIL On Condition

•	2 Driving Cycles

Specification

(Reference only)

Test Condition	HO2S Voltage(Sensor1)	HO2S Voltage(Sensor2)
HO2S Signal at idle after warm-up	Signal is normally switching from rich to lean more than 3 times in 10 sec.	Signal is normally above 0.6V.
HO2S signal at open circuit (Pumping current OFF)	Approx. 0.45V
HO2S signal at open circuit (Pumping current ON)	Approx. 3.5V

Schematic Diagram

Signal Waveform And Data

After warming-up, if accelerator pedal is released suddenly around 4000rpm, the HO2S signal reading will be lower than 200mV resulting from Fuel cut-off for the moment. Conversely, if suddenly accelerator pedal is depressed, HO2S signal reading will be around 0.6V ~ 1.0V. At idle, Normally HO2S signal will switch from lean to rich with 3 Hz. At higher engine RPM, the switching frequency increases.

Monitor DTC Status

Check DTC Status

(1)	Connect scantool to Data Link Connector(DLC).

(2)

IG "ON".

(3)	Select "DTC" button, and then Press "DTC Status" to check DTC's information from the DTCs menu.

(4)	Read "DTC Status" parameter.

(5)

Is parameter displayed "Present fault"?

	▶ Go to "Terminal and connector inspection" procedure.
	▶ Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.

Terminal And Connector Inspection

1.	Many malfunctions in the electrical system are caused by poor harness and terminal condition. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

2.	Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.

Has a problem been found?

	▶ Repair as necessary and go to "Verification of Vehicle Repair" procedure
	▶ Go to "Signal Circuit Inspection" procedure.

Signal Circuit Inspection

■ Check Open In Harness

1.	IG "OFF" and disconnect HO2S(B1/S1) connector.

2.	IG "ON" and ENG "OFF"

Measure voltage between signal termianl of HO2S(B1/S1) harness connector and chassis ground.

Specification :

Approx. 3.5V - when pumping current is ON

Approx. 0.45V - when pumping current is OFF

Is the measured voltage within specification?

	▶ Go to "Ground circuit inspection" procedure.
	▶ Repair open in harness, and go to "Verification of Vehicle Repair" prcedure.

Ground Circuit Inspection

■ Check Open In Harness

1.	IG "ON" and disconnect HO2S(B1/S1) connector.

2.	Measure voltage between signal terminal of HO2S(B1/S1) harness connector and chassis ground.(Measurement "A")

Measure voltage between signal and ground terminals of HO2S(B1/S1) harness connector.(Measurement "B")

Specification : Voltage difference between measurement "A" and "B" is below 200mV.

Is the measured voltage within specification?

	▶ Go to "Component inspection" procedure.
	▶ Repair open or contact resistance in harness, and go to "Verification of Vehicle Repair" prcedure.

Component Inspection

Check the Signal waveform of HO2S

(1)	IG "OFF" and connect HO2S connector.

(2)	Engine start.

(3)	After warming-up, monitor signal waveform of HO2S with scantool.

(4)

Is the sensor switching properly?

	▶ Go to "Check HO2S" as indicated below.
	▶ Substitute with a known - good HO2S and check for proper operation. If the problem is corrected, go to "Verification of Vehicle Repair" procedure.

Check HO2S

(1)	IG "OFF" and disconnect HO2S connector.

(2)	Check that the HO2S is securely installed.

(3)	Check the HO2S for contamination or damage

(4)

Is the sensor normal?

	▶ Substitute with a known - good PCM and check for proper operation. If the problem is corrected, go to "Verification of Vehicle Repair" procedure.
	▶ Substitute with a known - good HO2S and check for proper operation. If the problem is corrected, go to "Verification of Vehicle Repair" procedure.

There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM. Before or after testing PCM on the vehicle, use this function before reusing the PCM

Verification Of Vehicle Repair

After a repair, it is essential to verify that the fault has been corrected.

1.	Connect scantool and select "DTC" button.

2.	Press "DTC Status" button and confirm that "DTC Readiness Flag" indicates "Completed". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions

3.	Read "DTC Status" parameter

Is parameter displayed "History(Not Present) fault"?

	▶ System performing to specification at this time. Clear the DTC
	▶ Go to the applicable troubleshooting procedure.