DTC Code | DTC Name |
---|---|
P0031 | Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1) |
P0032 | Oxygen (A/F) Sensor Heater Control Circuit High (Bank 1 Sensor 1) |
P101D | A/F Sensor Heater Circuit Performance Bank 1 Sensor 1 Stuck ON |
DESCRIPTION
Refer to DTC P2195 Click here.
Tech Tips
When any of these DTCs are stored, the ECM enters fail-safe mode. The ECM turns off the air fuel ratio sensor heater in fail-safe mode. Fail-safe mode continues until the power switch is turned off.
Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio sensor.
The ECM has a pulse width modulated control circuit to adjust the current through the heater. The air fuel ratio sensor heater circuit uses a relay on the +B side of the circuit.
DTC No. | DTC Detection Condition | Trouble Area |
---|---|---|
P0031 | Air fuel ratio sensor heater current is less than 0.8 A, even when the air fuel ratio sensor heater output duty cycle is 30% or higher (1 trip detection logic). |
|
P0032 | Air fuel ratio sensor heater current reaches the high limit (Hybrid IC high current limiter monitor input "Fail") (1 trip detection logic). |
|
P101D | Air fuel ratio sensor heater current is higher than the specified value while the heater is not operating (1 trip detection logic). | ECM |
MONITOR DESCRIPTION
The ECM uses information from the air fuel ratio sensor to regulate the air fuel ratio and keep it close to the stoichiometric level. This maximizes the ability of the three-way catalytic converter to purify the exhaust gases.
The air fuel ratio sensor detects oxygen levels in the exhaust gas and transmits the information to the ECM. The inner surface of the sensor element is exposed to the outside air. The outer surface of the sensor element is exposed to the exhaust gas. The sensor element is made of platinum-coated zirconia and includes an integrated heating element.
The zirconia element generates a small voltage when there is a large difference in the oxygen concentrations between the exhaust gas and outside air. The platinum coating amplifies this voltage generation.
The air fuel ratio sensor is more efficient when heated. When the exhaust gas temperature is low, the sensor cannot generate useful voltage signals without supplementary heating. The ECM regulates the supplementary heating using a duty-cycle approach to adjust the average current in the sensor heater element. If the heater current is outside the normal range, the signal transmitted by the air fuel ratio sensor becomes inaccurate. As a result, the ECM is unable to regulate the air fuel ratio properly.
When the current in the air fuel ratio sensor heater is outside the normal operating range, the ECM interprets this as a malfunction in the sensor heater and stores a DTC.
MONITOR STRATEGY
Frequency of Operation | Continuous |
TYPICAL ENABLING CONDITIONS
Heater output duty cycle | 30% or higher |
Heater output duty cycle | Higher than 0% |
Heater duty cycle | 10% or higher, and less than 60% |
Heater on current | 0.8 A or higher |
CONFIRMATION DRIVING PATTERN
Connect the GTS to the DLC3.
Turn the power switch on (IG) and turn the GTS on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the power switch off and wait for at least 30 seconds.
Turn the power switch on (IG) and turn the GTS on [A].
Put the engine in inspection mode (maintenance mode) Click here.
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 2500 rpm for 1 minute [C].
Tech Tips
During charging control, the engine speed is set at idle. Therefore, the engine speed does not increase when depressing the accelerator pedal. In this case, perform steps [C] and [D] after charging control has completed.
Idle the engine for 5 minutes or more [D].
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [E].
Read the pending DTCs.
Tech Tips
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: P0031, P0032 or P101D.
Check the DTC judgment result.
GTS Display | Description |
---|---|
NORMAL |
|
ABNORMAL |
|
INCOMPLETE |
|
N/A |
|
Tech Tips
If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.
If the judgment result shows INCOMPLETE or N/A, perform steps [B] through [E] again.
WIRING DIAGRAM
CAUTION / NOTICE / HINT
Note
Inspect the fuses for circuits related to this system before performing the following inspection procedure.
Tech Tips
Refer to "Data List / Active Test" [A/F Heater Duty #1] Click here.
Sensor 1 refers to the sensor closest to the engine assembly.
Sensor 2 refers to the sensor farthest away from the engine assembly.
Read freeze frame data using the GTS. The ECM 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.
Change the fuel injection volume using the Control the Injection Volume for A/F Sensor function provided in the Active Test and monitor the air fuel ratio sensor output voltage Click here. If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.
PROCEDURE
INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)
Inspect the air fuel ratio sensor Click here.
Tech Tips
Perform "Inspection After Repair" after replacing the air fuel ratio sensor Click here.
NG |
REPLACE AIR FUEL RATIO SENSOR Click here |
OK |
CHECK TERMINAL VOLTAGE (POWER SOURCE OF AIR FUEL RATIO SENSOR)
*a | Front view of wire harness connector (to Air Fuel Ratio Sensor) |
Disconnect the air fuel ratio sensor connector.
Turn the power switch on (IG).
Measure the voltage according to the value(s) in the table below.
Standard Voltage | ||||||
---|---|---|---|---|---|---|
|
NG |
CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - NO. 1 INTEGRATION RELAY) Click here |
OK |
CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM)
Disconnect the air fuel ratio sensor connector.
Disconnect the ECM connector.
Measure the resistance according to the value(s) in the table below.
Standard Resistance | |||||||||
---|---|---|---|---|---|---|---|---|---|
|
NG |
REPAIR OR REPLACE HARNESS OR CONNECTOR |
OK |
CHECK WHETHER DTC OUTPUT RECURS (DTC P0031, P0032 OR P101D)
Connect the GTS to the DLC3.
Turn the power switch on (IG).
Turn the GTS on.
Clear the DTCs Click here.
Turn the power switch off and wait for at least 30 seconds.
Turn the power switch on (IG).
Turn the GTS on.
Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
Read the DTCs.
Result | Proceed to |
---|---|
DTC is not output | A |
DTC P0031, P0032 or P101D is output | B |
A |
CHECK FOR INTERMITTENT PROBLEMS Click here |
B |
REPLACE ECM Click here |
CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - NO. 1 INTEGRATION RELAY)
Disconnect the air fuel ratio sensor connector.
Remove the No. 1 integration relay from the engine room relay block and junction block assembly.
Measure the resistance according to the value(s) in the table below.
Standard Resistance | |||||||||
---|---|---|---|---|---|---|---|---|---|
|
NG |
REPAIR OR REPLACE HARNESS OR CONNECTOR |
OK |
CHECK TERMINAL VOLTAGE (POWER SOURCE OF NO. 1 INTEGRATION RELAY)
*a | Front view of wire harness connector (to No. 1 Integration Relay) |
Remove the No. 1 integration relay from the engine room relay block and junction block assembly.
Measure the voltage according to the value(s) in the table below.
Standard Voltage | ||||||
---|---|---|---|---|---|---|
|
OK |
REPLACE NO. 1 INTEGRATION RELAY Click here |
NG |
REPAIR OR REPLACE HARNESS OR CONNECTOR (AUXILIARY BATTERY - NO. 1 INTEGRATION RELAY) |