DESCRIPTION
The air fuel ratio sensor (sensor 1) generates current that corresponds to the actual air fuel ratio. This sensor current is used to provide the ECM with feedback so that it can control the air fuel ratio. The ECM determines the deviation from the stoichiometric air fuel ratio level, and regulates the fuel injection duration. If the air fuel ratio sensor (sensor 1) malfunctions, the ECM is unable to control the air fuel ratio accurately.
The air fuel ratio sensor (sensor 1) is a planar type sensor and integrated with the heater, which heats the solid electrolyte (zirconia element). This heater is controlled by the ECM. When the intake air volume is low (the exhaust gas temperature is low), a current flows into the heater to heat the sensor, in order to facilitate accurate oxygen concentration detection. In addition, the sensor and heater portions are a narrow type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, and thereby sensor activation is accelerated.
In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a three-way catalytic converter is used. For the most efficient use of the three-way catalytic converter, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric level.
HINT:
DTC No. | Detection Item |
DTC Detection Condition | Trouble Area |
MIL | Note |
---|---|---|---|---|---|
P003012 | HO2S Heater Control Bank 1 Sensor 1 Circuit Short to Battery |
The air fuel ratio sensor (sensor 1) heater current is more than the specified value while the heater is operating (1 trip detection logic). |
| Comes on |
|
P003013 |
HO2S Heater Control Bank 1 Sensor 1 Circuit Open |
The air fuel ratio sensor (sensor 1) heater current is less than the specified value while the heater is operating (1 trip detection logic). |
| Comes on |
|
P101A9E |
A/F Sensor Heater Performance Bank 1 Sensor 1 Stuck On |
The air fuel ratio sensor (sensor 1) heater voltage level is low while the heater is not operating (1 trip detection logic). |
| Comes on |
|
MONITOR DESCRIPTION
The ECM uses information from the air fuel ratio sensor (sensor 1) 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 (sensor 1) 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 (sensor 1) is more efficient when heated. When the exhaust gas temperature is low, the sensor cannot generate useful current 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 (sensor 1) 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 (sensor 1) heater is outside the normal operating range, the ECM interprets this as a malfunction in the sensor heater and stores a DTC.
MONITOR STRATEGY
Related DTCs | P0031: Air fuel ratio sensor (sensor 1) heater range check (low current) P0032: Air fuel ratio sensor (sensor 1) heater range check (high current) P101D: Air fuel ratio sensor (sensor 1) heater performance |
Required Sensors/Components (Main) | Air fuel ratio sensor (sensor 1) heater |
Required Sensors/Components (Related) | - |
Frequency of Operation | Continuous |
Duration | 10 seconds: P0031 and P0032 5 seconds: P101D |
MIL Operation | Immediate |
Sequence of Operation | None |
TYPICAL ENABLING CONDITIONS
P0031
All of the following conditions are met |
- |
Auxiliary battery voltage |
10.5 V or higher |
Time after heater on |
5 seconds or more |
Air fuel ratio sensor (sensor 1) heater performance fail (P101D, P103D) (Pending / MIL) |
Not detected |
Output duty cycle |
7% or higher |
Heater high current cutout |
Off |
Monitor runs whenever the following DTCs are not stored |
None |
All of the following conditions are met |
- |
Auxiliary battery voltage |
10.5 V or higher |
Time after heater on |
5 seconds or more |
CPU commanded duty cycle |
Higher than 7% |
Output duty cycle |
7% or higher |
Monitor runs whenever the following DTCs are not stored |
None |
Both of the following conditions are met |
- |
Auxiliary battery voltage |
10.5 V or higher |
Output duty cycle |
Less than 75% |
TYPICAL MALFUNCTION THRESHOLDS
P0031
Heater on current | Less than 0.6 A |
Heater on current | More than 14 A |
Heater terminal voltage level while heater off |
Low |
CONFIRMATION DRIVING PATTERN
HINT:
Click here
Click here
HINT:
GTS Display |
Description |
---|---|
NORMAL |
|
ABNORMAL |
|
INCOMPLETE |
|
HINT:
The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.
WIRING DIAGRAM
CAUTION / NOTICE / HINT
NOTICE:
Inspect the fuses for circuits related to this system before performing the following procedure.
HINT:
Click here
PROCEDURE
1. | INSPECT AIR FUEL RATIO SENSOR (SENSOR 1) (HEATER RESISTANCE) |
Click here
HINT:
Perform "Inspection After Repair" after replacing the air fuel ratio sensor (sensor 1).
Click here
NG | REPLACE AIR FUEL RATIO SENSOR (SENSOR 1) |
|
2. |
CHECK TERMINAL VOLTAGE (POWER SOURCE OF AIR FUEL RATIO SENSOR (SENSOR 1)) |
*a | Front view of wire harness connector (to Air Fuel Ratio Sensor (Sensor 1)) |
(a) Disconnect the air fuel ratio sensor (sensor 1) connector.
(b) Turn the ignition switch to ON.
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Tester Connection | Condition |
Specified Condition |
---|---|---|
C56-2 (+B) - Body ground |
Ignition switch ON | 11 to 14 V |
NG | GO TO STEP 6 |
|
3. |
CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR (SENSOR 1) - ECM) |
(a) Disconnect the air fuel ratio sensor (sensor 1) connector.
(b) Disconnect the ECM connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection | Condition |
Specified Condition |
---|---|---|
C56-1 (HA1A) - C76-9 (HA1A) |
Always | Below 1 Ω |
C56-1 (HA1A) or C76-9 (HA1A) - Body ground and other terminals |
Always | 10 kΩ or higher |
NG | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
4. |
CLEAR DTC |
(a) Clear the DTCs.
Powertrain > Engine > Clear DTCs(b) Turn the ignition switch off and wait for at least 30 seconds.
|
5. |
CHECK WHETHER DTC OUTPUT RECURS (DTC P003012, P003013 AND/OR P101A9E) |
(a) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
(b) Read the DTCs.
Powertrain > Engine > Trouble Codes
Result | Proceed to |
---|---|
DTCs are not output | A |
DTC P003012, P003013 and/or P101A9E is output |
B |
A | CHECK FOR INTERMITTENT PROBLEMS |
B | REPLACE ECM |
6. |
INSPECT EFI-MAIN NO. 2 RELAY |
Click here
NG |
REPLACE EFI-MAIN NO. 2 RELAY |
|
7. |
CHECK TERMINAL VOLTAGE (POWER SOURCE OF EFI-MAIN NO. 2 RELAY) |
*1 | No. 1 Engine Room Relay Block Assembly |
*2 | EFI-MAIN NO. 2 Relay |
(a) Remove the EFI-MAIN NO. 2 relay from the No. 1 engine room relay block assembly.
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Tester Connection | Condition |
Specified Condition |
---|---|---|
5 (EFI-MAIN NO. 2 relay) - Body ground |
Always | 11 to 14 V |
NG | REPAIR OR REPLACE HARNESS OR CONNECTOR (AUXILIARY BATTERY - EFI-MAIN NO. 2 RELAY) |
|
8. |
CHECK HARNESS AND CONNECTOR (EFI-MAIN NO. 2 RELAY - BODY GROUND) |
(a) Remove the EFI-MAIN NO. 2 relay from the No. 1 engine room relay block assembly.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection | Condition |
Specified Condition |
---|---|---|
2 (EFI-MAIN NO. 2 relay) - Body ground |
Always | Below 1 Ω |
NG | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
9. |
CHECK HARNESS AND CONNECTOR (EFI-MAIN NO. 2 RELAY - AIR FUEL RATIO SENSOR (SENSOR 1)) |
(a) Remove the EFI-MAIN NO. 2 relay from the No. 1 engine room relay block assembly.
(b) Disconnect the air fuel ratio sensor (sensor 1) connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection | Condition |
Specified Condition |
---|---|---|
3 (EFI-MAIN NO. 2 relay) - C56-2 (+B) |
Always | Below 1 Ω |
3 (EFI-MAIN NO. 2 relay) or C56-2 (+B) - Body ground and other terminals |
Always | 10 kΩ or higher |
OK | REPAIR OR REPLACE HARNESS OR CONNECTOR (EFI-MAIN NO. 1 RELAY - EFI-MAIN NO. 2 RELAY) |
NG | REPAIR OR REPLACE HARNESS OR CONNECTOR |