P0141
1NZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0037,P0038,P0141: Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2)
DESCRIPTION
- Refer to DTC P0136 P0136.
HINT
- Sensor 2 refers to the sensor mounted behind the Three-Way Catalytic Converter (TWC) and located far from the engine assembly.
- When any of these DTCs are set, the ECM enters fail-safe mode. The ECM turns off the Heated Oxygen (HO2) Sensor heater in fail-safe mode. Fail-safe mode continues until the ignition switch is turned to OFF.
- The ECM provides a pulse width modulated control circuit to adjust the current through the heater. The HO2 sensor heater circuit uses a relay on the B+ side of the circuit.
MONITOR DESCRIPTION
The sensing portion of the Heated Oxygen (HO2) sensor has a zirconia element which is used to detect the oxygen concentration in the exhaust gas. If the zirconia element is at the appropriate temperature, and the difference between the oxygen concentrations surrounding the inside and outside surfaces of the sensor is large, the zirconia element generates voltage signals. In order to increase the oxygen concentration detecting capacity of the zirconia element, the ECM supplements the heat from the exhaust with heat from a heating element inside the sensor.
Heated oxygen sensor heater range check (P0037 and P0038):
The ECM monitors the current applied to the HO2 sensor heater to check the heater for malfunctions. If the current is below the threshold value, the ECM determines that there is an open circuit in the heater. If the current is above the threshold value, the ECM determines that there is a short circuit in the heater.
The ECM constantly monitors the current applied to the heater. If the ECM detects an open or short circuit, the ECM turns the MIL on and sets a DTC.
If a malfunction is detected, the ECM cuts off the current applied to the heater.
Example:
The ECM sets DTC P0038 when the current in the HO2 sensor heater is more than 2 A. Conversely, when the heater current is less than 0.3 A, DTC P0037 is set.
Heated oxygen sensor heater performance (P0141):
After the accumulated heater ON time exceeds 100 seconds, the ECM calculates the heater resistance using the battery voltage and the current applied to the heater.
If the resistance is above the threshold value, the ECM determines that there is a malfunction in the HO2 sensor heater and sets DTC P0141.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
All:
All::
P0037:
P0037::
P0038:
P0038::
P0141 (Heater performance monitor check):
P0141 (Heater performance monitor check)::
TYPICAL MALFUNCTION THRESHOLDS
P0037:
P0037::
P0038:
P0038::
P0141 (Heater performance monitor check):
P0141 (Heater performance monitor check)::
COMPONENT OPERATING RANGE
MONITOR RESULT
Refer to Checking Monitor Status Mode 6 Data.
CONFIRMATION DRIVING PATTERN
- Connect the Techstream to the DLC3.
- Turn the ignition switch to ON and turn the Techstream on.
- Clear DTCs (even if no DTCs are stored, perform the clear DTC operation).
- Turn the ignition switch off and wait for at least 30 seconds.
- Turn the ignition switch to ON and turn the Techstream on [A].
- Start the engine and idle it for 5 minutes or more [B].
- With the vehicle stationary, depress the accelerator pedal and maintain an engine speed of 3000 rpm for 1 minute [C].
- Idle the engine for 5 minutes or more [D].
- Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [E].
- Read pending DTCs.
HINT
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.
- Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
- Input the DTC: P0037, P0038 or P0141.
- Check the DTC judgment result.
- If the judgment result shows INCOMPLETE or UNKNOWN, perform steps [B] through [E] again.
- If no pending DTC is output, perform a universal trip and check for permanent DTCs DTC Check / Clear.
HINT
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.
WIRING DIAGRAM
Refer to DTC P0136 P0136.
INSPECTION PROCEDURE
HINT
Read freeze frame data using a Techstream. Freeze frame data record the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data, from the time the malfunction occurred.
PROCEDURE
1. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)
(a) Disconnect the D28 Heated Oxygen (HO2) sensor connector.
(b) Measure the resistance of the HO2 sensor connector.
Standard resistance:
(c) Reconnect the HO2 sensor connector.
NG -- REPLACE HEATED OXYGEN SENSOR Removal
OK -- Continue to next step.
2. CHECK TERMINAL VOLTAGE (+B OF HO2 SENSOR)
(a) Disconnect the D28 HO2 sensor connector.
(b) Measure the voltage between the terminals of the D28 HO2 sensor connector and body ground.
Standard voltage:
(c) Reconnect the HO2 sensor connector.
OK -- CHECK HARNESS AND CONNECTOR (HO2 SENSOR - ECM)
NG -- Continue to next step.
3. INSPECT INTEGRATION RELAY (EFI RELAY) P0031
NG -- REPLACE INTEGRATION RELAY
OK -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (HO2 SENSOR - EFI RELAY)
(a) Disconnect the D28 HO2 sensor connector.
(b) Remove the integration relay from the engine room Relay Block (R/B).
(c) Check the resistance.
Standard resistance (Check for open):
Standard resistance (Check for short):
(d) Reconnect the HO2 sensor connector.
(e) Reinstall the integration relay.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- CHECK ECM POWER SOURCE CIRCUIT Component Tests and General Diagnostics
5. CHECK HARNESS AND CONNECTOR (HO2 SENSOR - ECM)
(a) Disconnect the D28 HO2 sensor connector.
(b) Disconnect the C20 ECM connector.
(c) Measure the resistance.
Standard resistance (Check for open):
Standard resistance (Check for short):
(d) Reconnect the HO2 sensor connector.
(e) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
6. CHECK WHETHER DTC OUTPUT RECURS (DTC P0037, P0038 AND/OR P0141)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Clear DTCs DTC Check / Clear.
(e) Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.
(f) Read DTCs.
Result:
B -- REPLACE ECM Removal
A -- CHECK FOR INTERMITTENT PROBLEMS