P0037
2AZ-FXE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0037,P0038,P0141: Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2)
P0141 - Oxygen Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)
DESCRIPTION
- Refer to DTC P0136 P0136.
HINT
- When any of these DTCs are set, the ECM (included in the hybrid vehicle control ECU) enters fail-safe mode. In fail-safe mode, the ECM turns off the Heated Oxygen (HO2) sensor heater. Fail-safe mode continues until the power switch is turned 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 position 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 (included in the hybrid vehicle control ECU) 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 O2 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.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
All:
All::
P0037:
P0037::
P0038 (Condition A):
P0038 (Condition A)::
P0038 (Condition B):
P0038 (Condition B)::
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
WIRING DIAGRAM
Refer to DTC P0136 P0136.
CONFIRMATION DRIVING PATTERN
These DTCs are detected when the engine idles for 110 seconds or more.
INSPECTION PROCEDURE
HINT
Sensor 2 refers to the sensor mounted behind the Three-Way Catalytic Converter (TWC) and located far from the engine assembly.
Read freeze frame data using the Techstream. The ECM (included in the hybrid vehicle control ECU) records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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 C22 Heated Oxygen (HO2) sensor connector.
(b) Measure the resistance according to the value(s) in the table below.
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 C22 HO2 sensor connector.
(b) Turn the power switch on (IG).
(c) Measure the voltage between the terminal of the C22 HO2 sensor connector and body ground.
Standard voltage:
(d) Reconnect the HO2 sensor connector.
OK -- CHECK HARNESS AND CONNECTOR (HO2 SENSOR - HYBRID VEHICLE CONTROL ECU)
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) Check the EFI No. 3 fuse.
(b) Disconnect the C22 HO2 sensor connector.
(c) Remove the integration relay from the engine room R/B and J/B.
(d) Measure the resistance.
Standard resistance (Check for open):
Standard resistance (Check for short):
(e) Reconnect the HO2 sensor connector.
(f) Reinstall the integration relay.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- CHECK ECM POWER SOURCE CIRCUIT
5. CHECK HARNESS AND CONNECTOR (HO2 SENSOR - HYBRID VEHICLE CONTROL ECU)
(a) Disconnect the C22 HO2 sensor connector.
(b) Disconnect the C64 hybrid vehicle control ECU connector.
(c) Measure the resistance.
Standard resistance (Check for open):
Standard resistance (Check for short):
(d) Reconnect the HO2 sensor connector.
(e) Reconnect the hybrid vehicle control ECU connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
6. CHECK WHETHER DTC OUTPUT RECURS
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the tester on.
(d) Clear the DTCs DTC Check / Clear.
(e) Put the engine in inspection mode Inspection Mode Procedure.
(f) Allow the engine to idle for 2 minutes or more.
(g) Select the following menu items: Powertrain / Engine / Trouble Code.
(h) Read the DTCs.
Result:
B -- REPLACE HYBRID VEHICLE CONTROL ECU Removal
A -- CHECK FOR INTERMITTENT PROBLEMS Check for Intermittent Problems