13A-DTC P0137: Heated Oxygen Sensor Circuit Low Voltage

DTC P0137: Heated Oxygen Sensor (rear) Circuit Low Voltage

CIRCUIT OPERATION

A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM terminal O2RL from the output terminal of the heated oxygen sensor (rear).
Ground terminal of the heated oxygen sensor (rear) is grounded with ECM terminal ORLE.
The ECM applies an offset voltage of 0.5 volt to ground terminal of the heated oxygen sensor (rear).

TECHNICAL DESCRIPTION

The output signal of the linear air-fuel ratio sensor is compensated by the output signal of the heated oxygen sensor (rear).
The ECM checks for the heated oxygen sensor (rear) output voltage.

DESCRIPTIONS OF MONITOR METHODS

Heated oxygen sensor (rear) output voltage is under the specified range.

MONITOR EXECUTION

Continuous

MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)

Linear air-fuel ratio sensor monitor
Linear air-fuel ratio sensor heater monitor
Heated oxygen sensor heater (rear) monitor
Heated oxygen sensor offset voltage monitor

Sensor (The sensor below is determined to be normal)

Mass airflow sensor
Engine coolant temperature sensor
Intake air temperature sensor
Barometric pressure sensor

DTC SET CONDITIONS

Logic Flow Chart

Check Conditions

Heated oxygen sensor offset voltage is between 0.4 and 0.6 volt.
Battery positive voltage is between 11 and 16.5 volts.
More than 65 - 335 seconds have passed since the engine starting sequence was completed.

Judgment Criterion

Heated oxygen sensor (rear) output voltage is less than 0.2 volt for 2 seconds.

FAIL-SAFE AND BACKUP FUNCTION

None

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 21 .

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)

Heated oxygen sensor (rear) failed.
Open or shorted circuit in heated oxygen sensor (rear) output line or harness damage.
Open circuit in heated oxygen sensor (rear) ground line or harness damage.
Connector damage.
ECM failed.

DIAGNOSIS

Required Special Tools:

MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
MB992745: V.C.I.-Lite main harness A
MB992747: V.C.I.-Lite USB cable short
MB992748: V.C.I.-Lite USB cable long
MB991958: Scan Tool (M.U.T.-III Sub Assembly)

MB991824: Vehicles Communication Interface (V.C.I.)
MB991827: M.U.T.-III USB Cable
MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)

MB991658: Test Harness

STEP 1. Using scan tool (M.U.T.-III), check data list item AD: Heated Oxygen Sensor (rear).

caution

To prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).

(1) Connect scan tool (M.U.T.-III). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III)

(2) Start the engine and run at idle.

(3) Set scan tool (M.U.T.-III) to the data reading mode for item AD, Heated Oxygen Sensor (rear).

Transaxle: 2nd (CVT: L range) speed
Drive with wide open throttle
Engine: 3,500 r/min or more

The output voltages should be between 0.6 and 1.0 volt.

(4) Turn the ignition switch to the "LOCK" (OFF) position.

Is the sensor operating properly?

It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions

Go to Step 2

STEP 2. Measure the sensor output voltage at heated oxygen sensor (rear) connector by backprobing.

(1) Do not disconnect the heated oxygen sensor (rear) connector.

(2) Start the engine and run at idle.

(3) Measure the voltage between terminal O2RL line and ground by backprobing under the following driving.

Transaxle: 2nd speed (CVT: L range)
Drive with wide open throttle
Engine: 3,500 r/min or more

The output voltage should be between 1.1 and 1.5 volts.

(4) Turn the ignition switch to the "LOCK" (OFF) position.

Is the measured voltage within the specified range?

Go to Step 3

Go to Step 4

STEP 3. Measure the sensor output voltage at ECM connector by backprobing.

(1) Do not disconnect the connector.

(2) Start the engine and run at idle.

(3) Measure the voltage between terminal O2RL and ground by backprobing under the following driving.

Transaxle: 2nd speed (CVT: L range)
Drive with wide open throttle
Engine: 3,500 r/min or more

The output voltage should be between 1.1 and 1.5 volts.

(4) Turn the ignition switch to the "LOCK" (OFF) position.

Is the measured voltage between 1.1 and 1.5 volts?

Go to Step 8

Repair or replace the connector(s), or check and repair the harness of open circuit and damage in O2RL line between heated oxygen sensor (rear) connector and ECM connector. Then go to Step 9

STEP 4. Measure the sensor offset voltage at heated oxygen sensor (rear) harness side connector.

(1) Disconnect the heated oxygen sensor (rear) connector and measure at the harness side.

(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal ORLE line and ground.

Voltage should be between 0.4 and 0.6 volt.

(4) Turn the ignition switch to the "LOCK" (OFF) position.

Is the measured voltage between 0.4 and 0.6 volt?

Go to Step 5

Repair or replace the connector(s), or check and repair the harness of open circuit in ORLE line between heated oxygen sensor (rear) connector and ECM connector. Then go to Step 9

STEP 5. Check of harness damage in ORLE line between heated oxygen sensor (rear) connector and ECM connector.

Is the harness wire in good condition?

Go to Step 6

Repair the connector(s) or wiring harness. Then go to Step 9

STEP 6. Check of short circuit to ground in O2RL line between heated oxygen sensor (rear) connector and ECM connector.

Is the harness wire in good condition?

Go to Step 7

Repair the connector(s) or wiring harness. Then go to Step 9

STEP 7. Check the heated oxygen sensor (rear).

(1) Disconnect the heated oxygen sensor (rear) connector and connect test harness special tool (MB991658) to the connector on the heated oxygen sensor (rear) side.

(2) Warm up the engine until engine coolant temperature reaches 80°C (176°F) or higher.

(3) Drive at 50 km/h (31mph) or more for 10 minutes.

(4) Connect a digital voltage meter between terminal O2RL line and terminal ORLE line.

(5) Measure the output voltage of heated oxygen sensor under the following driving.

Transaxle: 2nd speed (CVT: L range)
Drive with wide open throttle
Engine: 3,500 r/min or more

Standard value: 0.6 - 1.0 V

note	If the temperature of sensing area does not reach the high temperature [of approximately 400°C (752°F) or more] even though the heated oxygen sensor is normal, the output voltage would be possibly low in spite of the rich air-fuel ratio.

note	When the vehicle is driven with high loads, the temperature of the sensing area of the heated oxygen sensor is sufficiently high. Thus, it is not necessary to apply the voltage to the heater.

Is the measured voltage between 0.6 and 1.0 volt?

Go to Step 8

Replace the heated oxygen sensor (rear). Then go to Step 9

STEP 8. Using scan tool (M.U.T.-III), check data list item AD: Heated Oxygen Sensor (rear).

(1) Start the engine and run at idle.

(2) Set scan tool (M.U.T.-III) to the data reading mode for item AD, Heated Oxygen Sensor (rear).

Transaxle: 2nd speed (CVT: L range)
Drive with wide open throttle
Engine: 3,500 r/min or more

The output voltage should be between 0.6 and 1.0 volt.

(3) Turn the ignition switch to the "LOCK" (OFF) position.

Is the sensor operating properly?

It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions

Replace the ECM (Refer to, Removal and Installation

). Then go to Step 9

STEP 9. Test the OBD-II drive cycle.

(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 21

(2) Check the diagnostic trouble code (DTC).

Is DTC P0137 set?

Retry the troubleshooting.

The inspection is complete.