P0141
2AZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0037,P0038,P0141: Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2)
DTC P0037 - Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2)
DTC P0038 - Oxygen Sensor Heater Control Circuit High (Bank 1 Sensor 2)
DTC P0141 - Oxygen Sensor Heater Circuit Malfunction (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 HO2 sensor heater in fail-safe mode. Fail-safe mode continues until the ignition switch is turned off.
- The Heated Oxygen (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. When the current in the sensor heater is outside the standard operating range, the ECM interprets this as a malfunction in the sensor heater and sets a DTC.
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.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
All:
All::
P0037:
P0037::
P0038:
P0038::
P0141:
P0141::
TYPICAL MALFUNCTION THRESHOLDS
P0037:
P0037::
P0038:
P0038::
P0141 (Heater performance monitor check):
P0141 (Heater performance monitor check)::
COMPONENT OPERATING RANGE
WIRING DIAGRAM
Refer to DTC P0136 P0136.
INSPECTION PROCEDURE
HINT
Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
PROCEDURE
1. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)
(a) Disconnect the H5 Heated Oxygen (HO2) sensor connector.
(b) Measure the resistance between the terminals 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. INSPECT EFI RELAY
(a) Remove the EFI relay from the engine room relay block.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:
(c) Reinstall the EFI relay.
NG -- REPLACE EFI RELAY
OK -- Continue to next step.
3. INSPECT ECM (HT1B VOLTAGE)
(a) Turn the ignition switch to the ON position.
(b) Measure the voltage between the terminals of the E8 ECM connector.
Standard voltage:
NG -- CHECK WIRE HARNESS (HEATED OXYGEN SENSOR - ECM, EFI RELAY)
OK -- REPLACE ECM Removal
4. CHECK WIRE HARNESS (HEATED OXYGEN SENSOR - ECM, EFI RELAY)
(a) Check the wire harness between the ECM and HO2 sensor.
(1) Disconnect the H5 HO2 sensor connector.
(2) Disconnect the E8 ECM connector.
(3) Measure the resistance according to the value(s) in the table below.
Standard resistance:
(4) Reconnect the HO2 sensor connector.
(5) Reconnect the ECM connector.
(b) Check the wire harness between the HO2 sensor and EFI relay.
(1) Disconnect the H5 HO2 sensor connector.
(2) Remove the EFI relay from the engine room relay block.
(3) Measure the resistance according to the value(s) in the table below.
Standard resistance:
(4) Reconnect the HO2 sensor connector.
(5) Reinstall the EFI relay.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM Removal