DESCRIPTION
The Variable Valve Timing (VVT) system adjusts the intake valve timing to improve driveability. The engine oil pressure turns the VVT controller to adjust the valve timing.
The camshaft timing oil control valve is a solenoid valve and switches the engine oil line. The valve moves when the ECM applies 12 V to the solenoid. The ECM changes the energizing time to the solenoid (duty-cycle) in accordance with the camshaft position, crankshaft position, throttle position, etc.
Scheme 121
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P000A | Integrated deviations in target intake valve timing and actual intake valve timing per specified time exceed thresholds for 25 seconds (bank 1). (2 trip detection logic) | Valve timing Camshaft timing oil control valve (for intake side of bank 1) Oil control valve filter Camshaft timing gear assembly (for intake side of bank 1) ECM |
| P0011 | Deviation in target intake valve timing and actual intake valve timing exceeds thresholds (bank 1). (2 trip detection logic) | |
| P000C | Integrated deviations in target intake valve timing and actual intake valve timing per specified time exceed thresholds for 25 seconds (bank 2). (2 trip detection logic) | Valve timing camshaft timing oil control valve (for intake side of bank 2) Oil control valve filter Camshaft timing gear (for intake side of bank 2) ECM |
| P0021 | Deviation in target intake valve timing and actual intake valve timing exceeds thresholds (bank 2). (2 trip detection logic) |
MONITOR DESCRIPTION
- The ECM optimizes the intake valve timing using the Variable Valve Timing (VVT) system to control the intake camshaft. The VVT system includes the ECM, the camshaft timing oil control valve and the VVT controller (camshaft timing gear assembly). The ECM sends a target duty-cycle control signal to the camshaft timing oil control valve. This control signal regulates the oil pressure supplied to the VVT controller. The VVT controller can advance or retard the intake camshaft.
- If the difference between the target and actual intake valve timings is large, and changes in the actual intake valve timing are small, the ECM interprets this as the VVT controller stuck malfunction and stores a DTC.
- These DTCs indicate that the VVT controller cannot operate properly due to camshaft timing oil control valve malfunctions or the presence of foreign objects in the camshaft timing oil control valve.
The Variable Valve Timing (VVT) system adjusts the exhaust valve timing to improve driveability. The engine oil pressure turns the VVT controller to adjust the valve timing.
The camshaft timing oil control valve is a solenoid valve and switches the engine oil line. The valve moves when the ECM applies 12 V to the solenoid. The ECM changes the energizing time to the solenoid (duty-cycle) in accordance with the camshaft position, crankshaft position, throttle position, etc.
Scheme 122
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P000B | Integrated deviations in target exhaust valve timing and actual exhaust valve timing per specified time exceed threshold for 25 seconds (bank 1). (2 trip detection logic) | Valve timing Camshaft timing oil control valve (for exhaust side of bank 1) Camshaft oil control valve filter (bank 1) Camshaft timing gear assembly (for exhaust side of bank 1) ECM |
| P0014 | Deviation in target exhaust valve timing and actual exhaust valve timing exceeds threshold for 8 seconds (bank 1). (2 trip detection logic) | |
| P000D | Integrated deviations in target exhaust valve timing and actual exhaust valve timing per specified time exceed threshold for 25 seconds (bank 2). (2 trip detection logic) | Valve timing Camshaft timing oil control valve (for exhaust side of bank 2) Camshaft oil control valve filter (bank 2) Camshaft timing gear assembly (for exhaust side of bank 2) ECM |
| P0024 | Deviation in target exhaust valve timing and actual exhaust valve timing exceeds threshold for 8 seconds (bank 2). (2 trip detection logic) |
The ECM optimizes the exhaust valve timing using the Variable Valve Timing (VVT) system to control the exhaust camshaft. The VVT system includes the ECM, the camshaft timing oil control valve and the VVT controller (camshaft timing exhaust gear assembly). The ECM sends a target duty-cycle control signal to the camshaft timing oil control valve. This control signal regulates the oil pressure supplied to the VVT controller. The VVT controller can advance or retard the exhaust camshaft.
If the difference between the target and actual exhaust valve timing is large, and changes in the actual exhaust valve timing are small, the ECM interprets this as a VVT controller stuck malfunction and stores a DTC.
Refer to P000A. Refer to DESCRIPTION.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0010 | Oil control valve current is less than 0.306 A for intake camshaft circuit for 2 seconds or more (bank 1). (1 trip detection logic) | Open or short in camshaft timing oil control valve circuit (for intake side of bank 1) Camshaft timing oil control valve (for intake side of bank 1) ECM |
| P0020 | Oil control valve current is less than 0.306 A for intake camshaft circuit for 2 seconds or more (bank 2). (1 trip detection logic) | Open or short in camshaft timing oil control valve circuit (for intake side of bank 2) Camshaft timing oil control valve (for intake side of bank 2) ECM |
This DTC is designed to detect open or short in the camshaft timing oil control valve (for intake camshaft) circuit. If the camshaft timing oil control valve's duty-cycle is excessively high while the engine is running, the ECM will illuminate the MIL and store the DTC.
Refer to P000B. Refer to DESCRIPTION.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0013 | Oil control valve current is less than 0.306 A for exhaust camshaft circuit for 2 seconds or more (bank 1). (1 trip detection logic) | Open or short in camshaft timing oil control valve circuit (for exhaust side of bank 1) Camshaft timing oil control valve (for exhaust side of bank 1) ECM |
| P0023 | Oil control valve current is less than 0.306 A for exhaust camshaft circuit for 2 seconds or more (bank 2). (1 trip detection logic) | Open or short in camshaft timing oil control valve circuit (for exhaust side of bank 2) Camshaft timing oil control valve (for exhaust side of bank 2) ECM |
This DTC is designed to detect open or short in the camshaft timing oil control valve (for exhaust camshaft) circuit. If the camshaft timing oil control valve's duty-cycle is excessively high while the engine is running, the ECM will illuminate the MIL and store the DTC.
The VVT (Variable Valve Timing) system is composed of an ECM, camshaft timing oil control valve assembly, camshaft timing gear assembly (for intake side), and camshaft timing gear assembly (for exhaust side). This VVT system controls the operation of camshaft timing gear assembly (for intake and exhaust sides) to obtain optimum valve timing according to the driving conditions based on various sensor signals such as intake air volume, throttle position, and engine coolant temperature. The ECM controls the camshaft timing oil control valve assembly based on these signals, obtaining the optimum relative positions of the camshafts, in turn improving fuel economy, emission efficiency, and achieving higher output. In addition, the ECM detects the actual valve timing based on the signal from the camshaft position sensor and performs feedback control to obtain ideal valve timing.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0016 | Intake camshaft position has slipped from the threshold for 1 second (bank 1). (2 trip detection logic) | Valve timing Camshaft timing oil control valve (for intake side of bank 1) Oil control valve filter (bank 1) Camshaft timing gear assembly (for intake side of bank 1) ECM |
| P0017 | Exhaust camshaft position has slipped from the threshold for 5 seconds (bank 1). (2 trip detection logic) | Valve timing Camshaft timing oil control valve (for exhaust of bank 1) Oil control valve filter (bank 1) Camshaft timing gear assembly (for exhaust side of bank 1) ECM |
| P0018 | Intake camshaft position has slipped from the threshold for 1 second (bank 2). (2 trip detection logic) | Valve timing Camshaft timing oil control valve (for intake side of bank 2) Oil control valve filter (bank 2) Camshaft timing gear assembly (for intake side of bank 2) ECM |
| P0019 | Exhaust camshaft position has slipped from the threshold for 5 seconds (bank 2). (2 trip detection logic) | Valve timing Camshaft timing oil control valve (for exhaust side of bank 2) Oil control valve filter (bank 2) Camshaft timing gear assembly (for exhaust side of bank 2) ECM |
To monitor the correlation of the intake camshaft position and crankshaft position, the ECM checks the VVT neutral position against the VVT learning value while coasting. If the VVT neutral position is out of the specified VVT learning value range in driving cycles, the ECM illuminates the MIL and stores DTC P0016 (bank 1) or P0018 (bank 2).
To monitor the correlation of the exhaust camshaft position and crankshaft position, the ECM checks the VVT neutral position against VVT learning value while idling. If the VVT neutral position is out of the specified VVT learning value range in driving cycles, the ECM illuminates the MIL and stores DTC P0017 (bank 1) or P0019 (bank 2).
Refer to DTC P2195. Refer to DESCRIPTION .
HINT
- When any of these DTCs is 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 ignition switch is turned off.
- Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio sensor.
- Sensor 1 refers to the sensor mounted in front of the three-way catalytic converter and located near the engine assembly.
- The ECM provides 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 |
|---|---|---|
| P0030 | Air fuel ratio sensor impedance is greater than 65 ohms for 10 seconds or more. (2 trip detection logic) | Open or short in air fuel ratio sensor circuit Air fuel ratio sensor ECM |
| P0031 | Air fuel ratio sensor heater voltage is less than 1.9 V for 1 second or more. (1 trip detection logic) | |
| P0032 | Air fuel ratio sensor heater voltage is 1.9 V or more for 2 seconds or more. (1 trip detection logic) |
HINT
- Sensor 1 refers to the sensor closest to the engine assembly.
- Sensor 2 refers to the sensor farthest away from the engine assembly.
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.
Refer to DTC P0137. Refer to DESCRIPTION.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0037 | Heated oxygen sensor heater voltage is less than battery voltage X 0.3 V for 10 seconds or more. (2 trip detection logic) | Open or short in heated oxygen sensor heater circuit Heated oxygen sensor ECM |
| P0038 | Heated oxygen sensor heater voltage is battery voltage X 0.2 V or more for 2.56 seconds or more. (2 trip detection logic) | |
| P0141 | Heated oxygen sensor heater voltage is less than battery voltage X 0.88 V for 10 seconds or more. (2 trip detection logic) |
The sensing portion of the heated oxygen 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.
The ECM monitors the current applied to the heated oxygen sensor heater to check the heater for malfunctions.
If the heater current is outside the normal range, the signal transmitted by the heated oxygen sensor becomes inaccurate. When the current in the heated oxygen sensor heater is outside the normal operating range, the ECM interprets this as a malfunction in the sensor heater and stores a DTC.
Refer to DTC P0107. Refer to DESCRIPTION.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0068 | One of the following conditions is met (2 trip detection logic): Manifold absolute pressure sensor voltage is less than 1.25 V for 5 seconds or more when throttle position is 10° or more. Manifold absolute pressure sensor voltage is more than 3.3 V for 5 seconds or more when throttle position is less than 5.13°. | Open or short in manifold absolute pressure sensor circuit Manifold absolute pressure sensor ECM |
The manifold absolute pressure sensor is affixed to the intake manifold.
If the manifold absolute pressure is low in spite of driving conditions that would suggest this would be high, or if this is high in spite of driving conditions that would suggest this would be low, then this DTC is detected.
The high-pressure fuel system consists of the spill control valve, pump plunger and fuel pressure sensor. The spill control valve opens and closes the low-pressure fuel line (from the fuel tank), the pump plunger (operated by the camshaft) pressurizes fuel and the fuel pressure sensor located on the fuel delivery pipe monitors fuel pressure.
The fuel pump assembly (for high pressure) is installed to the cylinder head cover (bank 2) and is driven by the cam located at the intake camshaft.
The plunger moves up and down by the camshaft rotations, and produces a vacuum to suck fuel and pressurizes the fuel. This fuel flows into the fuel delivery pipe. The ECM opens and closes the spill control valve to regulate the fuel pressure to the target fuel pressure. In order to obtain and maintain the target pressure, the ECM monitors the fuel pressure using the fuel pressure sensor and performs the feedback control.
HINT
The spill control valve, pump plunger are built into the fuel pump assembly (for high pressure).
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0087 | Fuel pressure is lower than the target value. (1 trip detection logic) | Leak of fuel Fuel pipe (Fuel tank - Fuel pump assembly (for high pressure) [bank 1 or bank 2]) Fuel pipe (Fuel pump assembly (for high pressure) - Fuel injector assembly [for direct injection]) Fuel injector assembly (for direct injection) Fuel pump assembly (for high pressure) Injector driver (EDU) Fuel pump assembly ECM |
If the fuel pressure decreases even after the ECM commands the high-pressure fuel pump to close the spill control valve, a DTC is output.
Refer to DTC P0087. Refer to DESCRIPTION.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0088 | Fuel pressure is higher than the target value for 10 seconds or more. (1 trip detection logic) | Fuel pump assembly (for high pressure) ECM |
If the fuel pressure does not decrease even after the ECM commands the high-pressure fuel pump to open the spill control valve, a DTC is output.
If there is minimal difference between the fuel pressure before and after the fuel relief valve operates, a DTC is output.
Refer to DTC P0102. Refer to DESCRIPTION.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0101 | One of the following conditions is met (2 trip detection logic): Mass air flow meter voltage is less than 1.13 V for 5 seconds or more when throttle position is 16° or more with driving. Mass air flow meter voltage is more than 1.88 V for 5 seconds or more when throttle position is less than 5.13°. | Mass air flow meter Intake system PCV hose connections |
The mass air flow meter is a sensor that measures the amount of air flowing through the throttle valve. The ECM uses this information to determine the fuel injection time and to provide an appropriate air fuel ratio. Inside the mass air flow meter, there is a heated platinum wire which is exposed to the flow of intake air. By applying a specific electrical current to the wire, the ECM heats it to a specific temperature. The flow of incoming air cools both the wire and an internal thermistor, affecting their resistance. To maintain a constant current value, the ECM varies the voltage applied to the mass air flow meter. The voltage level is proportional to the airflow through the sensor, and the ECM uses it to calculate the intake air volume.
The ECM monitors the average engine load value ratio to check the mass air flow meter for malfunctions. The average engine load value ratio is obtained by comparing the average engine load calculated from the MAF meter output to the average engine load estimated from the driving conditions, such as the engine speed and the throttle opening angle. If the average engine load value ratio is below the threshold value, the ECM determines that the intake air volume is low, and if the average engine load value ratio is above the threshold value, the ECM determines that the intake air volume is high.
If this is detected in 2 consecutive driving cycles, the MIL is illuminated and the DTC is stored.
Refer to DTC P0102. Refer to DESCRIPTION.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0101 | One of the following conditions is met (2 trip detection logic): Mass air flow meter voltage is less than 1.13 V for 5 seconds or more when throttle position is 10° or more with driving. Mass air flow meter voltage is more than 1.88 V for 10 seconds or more when throttle position is less than 3.8°. | Mass air flow meter Intake system PCV hose connections |
The mass air flow meter is a sensor that measures the amount of air flowing through the throttle valve. The ECM uses this information to determine the fuel injection time and to provide an appropriate air fuel ratio. Inside the mass air flow meter, there is a heated platinum wire which is exposed to the flow of intake air. By applying a specific electrical current to the wire, the ECM heats it to a specific temperature. The flow of incoming air cools both the wire and an internal thermistor, affecting their resistance. To maintain a constant current value, the ECM varies the voltage applied to the mass air flow meter. The voltage level is proportional to the airflow through the sensor, and the ECM uses it to calculate the intake air volume.
The ECM monitors the average engine load value ratio to check the mass air flow meter for malfunctions. The average engine load value ratio is obtained by comparing the average engine load calculated from the MAF meter output to the average engine load estimated from the driving conditions, such as the engine speed and the throttle opening angle. If the average engine load value ratio is below the threshold value, the ECM determines that the intake air volume is low, and if the average engine load value ratio is above the threshold value, the ECM determines that the intake air volume is high.
If this is detected in 2 consecutive driving cycles, the MIL is illuminated and the DTC is stored.
The mass air flow meter is a sensor that measures the amount of air flowing through the throttle valve. The ECM uses this information to determine the fuel injection time and to provide the appropriate air fuel ratio.
Inside the mass air flow meter, there is a heated platinum wire which is exposed to the flow of intake air. By applying a specific electrical current to the wire, the ECM heats it to a given temperature. The flow of incoming air cools both the wire and an internal thermistor, affecting their resistance. To maintain a constant current value, the ECM varies the voltage applied to the wire and internal thermistor. The voltage level is proportional to the airflow through the sensor, and the ECM uses it to calculate the intake air volume.
The circuit is constructed so that the platinum hot wire and the temperature sensor create a bridge circuit, and the power transistor is controlled so that the potentials of A and B remain equal to maintain the predetermined temperature.
HINT
When any of these DTCs is stored, the ECM enters fail-safe mode. During fail-safe mode, the ignition timing is calculated by the ECM, according to the engine speed and throttle valve position. Fail-safe mode continues until a pass condition is detected.
Scheme 123
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0102 | Mass air flow meter voltage is 0.1 V or less for 0.5 seconds or more. (1 trip detection logic) | Open or short in mass air flow meter circuit Mass air flow meter ECM |
| P0103 | Mass air flow meter voltage is 4.7 V or more for 0.5 seconds or more. (1 trip detection logic) |
HINT
When any of these DTCs are output, check the air-flow rate using the Techstream. Enter the following menus: Powertrain / Engine / Data List / MAF.
| Mass Air Flow Rate (gm/sec) | Malfunction |
|---|---|
| Approximately 0.0 | Open in mass air flow meter power source circuit Open or short in VG circuit |
| 160.0 or more | Open in E2G circuit |
If there is a defect in the mass air flow meter or an open or short circuit, the voltage level deviates from the normal operating range. The ECM interprets this deviation as a malfunction in the mass air flow meter circuit and stores a DTC.
Manifold absolute pressure sensor uses a built-in sensor to detect the intake manifold pressure as a voltage. Additionally, because this measures the absolute pressure as the pressure within the intake manifold without detecting the atmospheric pressure as a standard value, this enables measurements without being influenced by changes in atmospheric pressure from altitude or other causes.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0107 | Manifold absolute pressure sensor voltage is 0.6 V or less for 2 seconds or more. (1 trip detection logic) | Open or short in manifold absolute pressure sensor circuit Manifold absolute pressure sensor ECM |
| P0108 | Manifold absolute pressure sensor voltage is 3.9 V or more for 2 seconds or more. (1 trip detection logic) |
HINT
When any of these DTCs are output, check the manifold absolute pressure using the Techstream. Enter the following menus: Powertrain / Engine / Data List / MAP.
| Manifold Absolute Pressure (kPa [mmHg]) | Malfunction |
|---|---|
| Approximately 0 [0] | Short in MAP circuit |
| 141 [1058] or more | Short in VC circuit Open in PIM circuit Open in E1 circuit |
The ECM calculates the manifold absolute pressure based upon the manifold absolute pressure sensor output voltage. If the manifold absolute pressure output voltage is outside the normal range, there may be an abnormality with the manifold absolute pressure, or an open or short in the circuit. In these cases, the ECM will light the check engine warning light, and store the DTC.
- The intake air temperature sensor, mounted on the mass air flow meter, monitors the intake air temperature. The intake air temperature sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the intake air temperature is low, the resistance of the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are transmitted to the ECM as voltage changes.
- The intake air temperature sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor R.
- Resistor R and the intake air temperature sensor are connected in series. When the resistance value of the intake air temperature sensor changes, according to changes in the intake air temperature, the voltage at terminal THA also varies. Based on this signal, the ECM increases the fuel injection volume when the engine is cold to improve driveability.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0111 | The difference between maximum and minimum values for inlet air temperature sensor voltage is less than 0.02 V. (2 trip detection logic) | Mass air flow meter |
The ECM performs OBD II monitoring based on the values from the intake air temperature sensor. If there is no change of the sensor value within the normal range, the ECM will not be able to perform OBD II monitoring or will misdiagnose that there is a malfunction in the sensor. The ECM detects when the intake air temperature sensor value is stuck by performing monitoring after the ignition switch is turned off or the engine is started (short soak or long soak).
- The intake air temperature sensor, mounted on the mass air flow meter, monitors the intake air temperature. The intake air temperature sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the intake air temperature is low, the resistance of the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are transmitted to the ECM as voltage changes.
- The intake air temperature sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor R.
- Resistor R and the intake air temperature sensor are connected in series. When the resistance value of the intake air temperature sensor changes, according to changes in the intake air temperature, the voltage at terminal THA also varies. Based on this signal, the ECM increases the fuel injection volume when the engine is cold to improve driveability.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0111 | The difference between maximum and minimum values for inlet air temperature sensor voltage is less than 0.02 V. (2 trip detection logic) | Mass air flow meter |
The ECM performs OBD II monitoring based on the values from the intake air temperature sensor. If there is no change of the sensor value within the normal range, the ECM will not be able to perform OBD II monitoring or will misdiagnose that there is a malfunction in the sensor. The ECM detects when the intake air temperature sensor value is stuck by performing monitoring after the ignition switch is turned off or the engine is started (short soak or long soak).
- The intake air temperature sensor, mounted on the mass air flow meter, monitors the intake air temperature. The intake air temperature sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the intake air temperature is low, the resistance of the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are transmitted to the ECM as voltage changes.
- The intake air temperature sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor.
- Resistor and the intake air temperature sensor are connected in series. When the resistance value of the intake air temperature sensor changes, according to changes in the intake air temperature, the voltage at terminal THA also varies. Based on this signal, the ECM increases the fuel injection volume when the engine is cold to improve driveability. HINT: When DTC P0112 or P0113 is stored, the ECM enters fail-safe mode. During fail-safe mode, the intake air temperature is estimated to be 20°C (68°F) by the ECM. Fail-safe mode continues until a pass condition is detected.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0112 | Intake air temperature sensor voltage is less than 0.4 V for 0.5 seconds or more. (1 trip detection logic) | Open or short in intake air temperature sensor circuit Intake air temperature sensor (built into mass air flow meter) ECM |
| P0113 | Intake air temperature sensor voltage is 4.7 V or more for 0.5 seconds or more. (1 trip detection logic) |
HINT
When any of these DTCs are output, check the intake air temperature using the Techstream. Enter the following menus: Powertrain / Engine / Data List / Intake Air.
| Temperature Displayed | Malfunction |
|---|---|
| 40°C (-40°F) | Open circuit |
| 120°C (248°F) | Short circuit |
The ECM monitors the sensor voltage and uses this value to calculate the intake air temperature. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a malfunction in the intake air temperature sensor circuit and stores a DTC.
- The intake air temperature sensor, mounted on the mass air flow meter, monitors the intake air temperature. The intake air temperature sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the intake air temperature is low, the resistance of the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are transmitted to the ECM as voltage changes.
- The intake air temperature sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor.
- Resistor and the intake air temperature sensor are connected in series. When the resistance value of the intake air temperature sensor changes, according to changes in the intake air temperature, the voltage at terminal THA also varies. Based on this signal, the ECM increases the fuel injection volume when the engine is cold to improve driveability. HINT: When DTC P0112 or P0113 is stored, the ECM enters fail-safe mode. During fail-safe mode, the intake air temperature is estimated to be 20°C (68°F) by the ECM. Fail-safe mode continues until a pass condition is detected.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0112 | Intake air temperature sensor voltage is less than 0.4 V for 0.5 seconds or more. (1 trip detection logic) | Open or short in intake air temperature sensor circuit Intake air temperature sensor (built into mass air flow meter) ECM |
| P0113 | Intake air temperature sensor voltage is 4.7 V or more for 0.5 seconds or more. (1 trip detection logic) |
HINT
When any of these DTCs are output, check the intake air temperature using the Techstream. Enter the following menus: Powertrain / Engine / Data List / Intake Air.
| Temperature Displayed | Malfunction |
|---|---|
| 40°C (-40°F) | Open circuit |
| 120°C (248°F) | Short circuit |
The ECM monitors the sensor voltage and uses this value to calculate the intake air temperature. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a malfunction in the intake air temperature sensor circuit and stores a DTC.
Refer to DTC P0117. Refer to DESCRIPTION.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0116 | The engine coolant temperature has not dropped completely 6 hours after ignition switch turned off. (2 trip detection logic) | Thermostat Engine coolant temperature sensor |
If the engine coolant temperature sensor value does not change after the warmed up engine is stopped and then the next cold engine start is performed, it is determined that a malfunction has occurred. If this is detected in 2 consecutive driving cycles, the MIL is illuminated and the DTC is stored.
Refer to DTC P0117. Refer to DTC P0117: Engine Coolant Temperature Circuit Low Input; DTC P0118: Engine Coolant Temperature Circuit High Input.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0116 | The engine coolant temperature has not dropped completely 6 hours after ignition switch turned off. (2 trip detection logic) | Thermostat Engine coolant temperature sensor |
If the engine coolant temperature sensor value does not change after the warmed up engine is stopped and then the next cold engine start is performed, it is determined that a malfunction has occurred. If this is detected in 2 consecutive driving cycles, the MIL is illuminated and the DTC is stored.
A thermistor, whose resistance value varies according to the engine coolant temperature, is built into the engine coolant temperature sensor. The structure of the sensor and its connection to the ECM are the same as those of the intake air temperature sensor.
HINT
When any of DTCs P0117 and P0118 is stored, the ECM enters fail-safe mode. During fail-safe mode, the engine coolant temperature is estimated to be 70°C (158°F) by the ECM. Fail-safe mode continues until a pass condition is detected.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0117 | Engine coolant temperature sensor voltage is less than 0.5 V for 0.5 seconds or more. (1 trip detection logic) | Short in engine coolant temperature sensor circuit Engine coolant temperature sensor ECM |
| P0118 | Engine coolant temperature sensor voltage is more than 4.7 V for 0.5 seconds or more. (1 trip detection logic) | Open in engine coolant temperature sensor circuit Engine coolant temperature sensor ECM |
HINT
When any of these DTCs are output, check the engine coolant temperature using the Techstream. Enter the following menus: Powertrain / Engine / Data List / Coolant Temp.
| Temperature Displayed | Malfunction |
|---|---|
| 40°C (-40°F) | Open circuit |
| 120°C (248°F) | Short circuit |
The engine coolant temperature sensor is used to monitor the engine coolant temperature. The engine coolant temperature sensor has a thermistor with a resistance that varies according to the temperature of the engine coolant. When the coolant temperature is low, the resistance in the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are reflected in the output voltage from the sensor. The ECM monitors the sensor voltage and uses this value to calculate the engine coolant temperature. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a fault in the engine coolant temperature sensor circuit and stores a DTC.
A thermistor, whose resistance value varies according to the engine coolant temperature, is built into the engine coolant temperature sensor. The structure of the sensor and its connection to the ECM are the same as those of the intake air temperature sensor.
HINT
When any of DTCs P0117 and P0118 is stored, the ECM enters fail-safe mode. During fail-safe mode, the engine coolant temperature is estimated to be 70°C (158°F) by the ECM. Fail-safe mode continues until a pass condition is detected.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0117 | Engine coolant temperature sensor voltage is less than 0.5 V for 0.5 seconds or more. (1 trip detection logic) | Short in engine coolant temperature sensor circuit Engine coolant temperature sensor ECM |
| P0118 | Engine coolant temperature sensor voltage is more than 4.7 V for 0.5 seconds or more. (1 trip detection logic) | Open in engine coolant temperature sensor circuit Engine coolant temperature sensor ECM |
HINT
When any of these DTCs are output, check the engine coolant temperature using the Techstream. Enter the following menus: Powertrain / Engine / Data List / Coolant Temp.
| Temperature Displayed | Malfunction |
|---|---|
| 40°C (-40°F) | Open circuit |
| 120°C (248°F) | Short circuit |
The engine coolant temperature sensor is used to monitor the engine coolant temperature. The engine coolant temperature sensor has a thermistor with a resistance that varies according to the temperature of the engine coolant. When the coolant temperature is low, the resistance in the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are reflected in the output voltage from the sensor. The ECM monitors the sensor voltage and uses this value to calculate the engine coolant temperature. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a fault in the engine coolant temperature sensor circuit and stores a DTC.
HINT
These DTCs relate to the throttle position sensor.
The throttle position sensor is mounted on the throttle with motor body assembly, and detects the opening angle of the throttle valve. This sensor is a non-contact type sensor. It uses Hall-effect elements in order to yield accurate signals even in extreme driving conditions, such as at high speeds as well as very low speeds.
The throttle position sensor has 2 sensor circuits, each of which transmits a signal, VTA1 and VTA2. VTA1 is used to detect the throttle valve angle and VTA2 is used to detect malfunctions in VTA2. The sensor signal voltages vary between 0 V and 5 V in proportion to the throttle valve opening angle, and are transmitted to the VTA1 and VTA2 terminals of the ECM.
As the valve closes, the sensor output voltage decreases and as the valve opens, the sensor output voltage increases. The ECM calculates the throttle valve opening angle according to these signals and controls the throttle actuator in response to driver inputs. These signals are also used in calculations such as air fuel ratio correction, power increase correction and fuel-cut control.
Scheme 124
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0122 | The voltage of VTA1 is 0.3 V or less for 0.024 seconds or more. (1 trip detection logic) | Throttle position sensor (built into throttle with motor body assembly) Short in VTA1 circuit Open in VC circuit ECM |
| P0123 | The voltage of VTA1 is more than 4.7 V for 0.024 seconds or more. (1 trip detection logic) | Throttle position sensor (built into throttle with motor body assembly) Open in VTA1 circuit Open in E1 circuit Short between VC and VTA1 circuits ECM |
| P0222 | The voltage of VTA2 is 1.2 V or less for 0.024 seconds or more. (1 trip detection logic) | Throttle position sensor (built into throttle with motor body assembly) Short in VTA2 circuit Open in VC circuit ECM |
| P0223 | The voltage of VTA2 is 4.8 V or more for 0.024 seconds or more. (1 trip detection logic) | Throttle position sensor (built into throttle with motor body assembly) Open in VTA2 circuit Open in E1 circuit Short between VC and VTA2 circuits ECM |
| P2135 | Deviation in voltages of VTA1 and VTA2 exceed thresholds for 0.212 seconds or more. (1 trip detection logic) | Short between VTA1 and VTA2 circuits Throttle position sensor (built into throttle with motor body assembly) ECM |
HINT
- When any of these DTCs are output, check the throttle valve opening angle using the Techstream. Enter the following menus: Powertrain / Engine / Data List / Throttle Position No. 1 and Throttle Position No. 2.
- Throttle Position No. 1 is the VTA1 signal, and Throttle Position No. 2 is the VTA2 signal. Reference (Normal Condition) Techstream Display Accelerator Pedal Fully Released Accelerator Pedal Fully Depressed Throttle Position No. 1 0.213 to 4.772 V 0.213 to 4.772 V Throttle Position No. 2 0.213 to 4.772 V 0.213 to 4.772 V
The ECM uses the throttle position sensor to monitor the throttle valve opening angle. There are several checks that the ECM performs to confirm the proper operation of the throttle position sensor.
- A specific voltage difference is expected between the sensor terminals, VTA1 and VTA2, for each throttle valve opening angle. If the difference between VTA1 and VTA2 is incorrect, the ECM interprets this as a malfunction in the sensor circuit, and stores a DTC.
- VTA1 and VTA2 each have a specific voltage range. If VTA1 or VTA2 is outside the normal operating range, the ECM interprets this as a malfunction in the sensor circuit, and stores a DTC.
- VTA1 and VTA2 should never be close to the same voltage level. If VTA1 is within 0.02 V of VTA2, the ECM determines that there is a short circuit in the sensor circuit, and stores a DTC.
HINT
These DTCs relate to the throttle position sensor.
The throttle position sensor is mounted on the throttle with motor body assembly, and detects the opening angle of the throttle valve. This sensor is a non-contact type sensor. It uses Hall-effect elements in order to yield accurate signals even in extreme driving conditions, such as at high speeds as well as very low speeds.
The throttle position sensor has 2 sensor circuits, each of which transmits a signal, VTA1 and VTA2. VTA1 is used to detect the throttle valve angle and VTA2 is used to detect malfunctions in VTA2. The sensor signal voltages vary between 0 V and 5 V in proportion to the throttle valve opening angle, and are transmitted to the VTA1 and VTA2 terminals of the ECM.
As the valve closes, the sensor output voltage decreases and as the valve opens, the sensor output voltage increases. The ECM calculates the throttle valve opening angle according to these signals and controls the throttle actuator in response to driver inputs. These signals are also used in calculations such as air fuel ratio correction, power increase correction and fuel-cut control.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0122 | The voltage of VTA1 is 0.3 V or less for 0.024 seconds or more. (1 trip detection logic) | Throttle position sensor (built into throttle with motor body assembly) Short in VTA1 circuit Open in VC circuit ECM |
| P0123 | The voltage of VTA1 is more than 4.7 V for 0.024 seconds or more. (1 trip detection logic) | Throttle position sensor (built into throttle with motor body assembly) Open in VTA1 circuit Open in E1 circuit Short between VC and VTA1 circuits ECM |
| P0222 | The voltage of VTA2 is 1.2 V or less for 0.024 seconds or more. (1 trip detection logic) | Throttle position sensor (built into throttle with motor body assembly) Short in VTA2 circuit Open in VC circuit ECM |
| P0223 | The voltage of VTA2 is 4.8 V or more for 0.024 seconds or more. (1 trip detection logic) | Throttle position sensor (built into throttle with motor body assembly) Open in VTA2 circuit Open in E1 circuit Short between VC and VTA2 circuits ECM |
| P2135 | Deviation in voltages of VTA1 and VTA2 exceed thresholds for 0.212 seconds or more. (1 trip detection logic) | Short between VTA1 and VTA2 circuits Throttle position sensor (built into throttle with motor body assembly) ECM |
HINT
- When any of these DTCs are output, check the throttle valve opening angle using the Techstream. Enter the following menus: Powertrain / Engine / Data List / Throttle Position No. 1 and Throttle Position No. 2.
- Throttle Position No. 1 is the VTA1 signal, and Throttle Position No. 2 is the VTA2 signal. Reference (Normal Condition) Techstream Display Accelerator Pedal Fully Released Accelerator Pedal Fully Depressed Throttle Position No. 1 0.213 to 4.772 V 0.213 to 4.772 V Throttle Position No. 2 0.213 to 4.772 V 0.213 to 4.772 V
The ECM uses the throttle position sensor to monitor the throttle valve opening angle. There are several checks that the ECM performs to confirm the proper operation of the throttle position sensor.
- A specific voltage difference is expected between the sensor terminals, VTA1 and VTA2, for each throttle valve opening angle. If the difference between VTA1 and VTA2 is incorrect, the ECM interprets this as a malfunction in the sensor circuit, and stores a DTC.
- VTA1 and VTA2 each have a specific voltage range. If VTA1 or VTA2 is outside the normal operating range, the ECM interprets this as a malfunction in the sensor circuit, and stores a DTC.
- VTA1 and VTA2 should never be close to the same voltage level. If VTA1 is within 0.02 V of VTA2, the ECM determines that there is a short circuit in the sensor circuit, and stores a DTC.
Refer to DTC P0117. Refer to DESCRIPTION.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0125 | Despite estimated engine coolant temperature is -15°C (-59°F) or more, engine coolant temperature sensor value is less than -15°C (-59°F) for 300 seconds or more. (2 trip detection logic) | Cooling system Engine coolant temperature sensor Thermostat |
The diagnostic system monitors for a functional check of the engine coolant temperature sensor. If the engine coolant temperature does not reach the temperature to enable the closed loop air/fuel ratio control within a predetermined time after engine start, the diagnostic system determines a malfunction of engine coolant temperature sensor and stores the DTC.
Refer to DTC P0117. Refer to DESCRIPTION.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0125 | Despite estimated engine coolant temperature is 20°C (68°F) or more, engine coolant temperature sensor value is less than 20°C (68°F) for 300 seconds or more. (2 trip detection logic) | Cooling system Engine coolant temperature sensor Thermostat |
The diagnostic system monitors for a functional check of the engine coolant temperature sensor. If the engine coolant temperature does not reach the temperature to enable the closed loop air/fuel ratio control within a predetermined time after engine start, the diagnostic system determines a malfunction of engine coolant temperature sensor and stores the DTC.
At the same time as using the engine coolant temperature sensor to determine the engine coolant temperature, the ECM estimates the engine coolant temperature. If the difference between the estimated and actual engine coolant temperatures exceeds a predetermined value, then the DTC is stored, notifying of a malfunction in the functioning of the thermostat.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0128 | Abnormal (open) thermostat functioning detected. (2 trip detection logic) | Thermostat Cooling system Engine coolant temperature sensor ECM |
The ECM estimates the engine coolant temperature based on the starting temperature, engine loads, and engine speeds. The ECM then compares the estimated temperature with the actual engine coolant temperature. If the difference between the estimated engine coolant temperature and the actual engine coolant temperature exceeds the specified value, the ECM interprets this as a malfunction in the thermostat or the engine cooling system and stores the DTC.
At the same time as using the engine coolant temperature sensor to determine the engine coolant temperature, the ECM estimates the engine coolant temperature. If the difference between the estimated and actual engine coolant temperatures exceeds a predetermined value, then the DTC is stored, notifying of a malfunction in the functioning of the thermostat.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0128 | Abnormal (open) thermostat functioning detected. (2 trip detection logic) | Thermostat Cooling system Engine coolant temperature sensor ECM |
The ECM estimates the engine coolant temperature based on the starting temperature, engine loads, and engine speeds. The ECM then compares the estimated temperature with the actual engine coolant temperature. If the difference between the estimated engine coolant temperature and the actual engine coolant temperature exceeds the specified value, the ECM interprets this as a malfunction in the thermostat or the engine cooling system and stores the DTC.
- Refer to DTC P2195. Refer to «DESCRIPTION»(/scion/fr-s/i-2012-2016/remont/testing-diagnostics/#engine-control-system-diagnostic-codes-p1604-u0155-circuit-tests) . HINT: Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio sensor. Sensor 1 refers to the sensor mounted in front of the three-way catalytic converter and located near the engine assembly.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0131 | One of the following conditions is met for 1 second or more (1 trip detection logic): The voltage of A1A+ is less than 0.4 V. The voltage of A1A- is less than 0.4 V. The difference between voltage of A1A+ and voltage of A1A- is less than 0.1 V and the voltage of A1A- is more than 3.8 V and less than 4.7 V. | Open or short in air fuel ratio sensor circuit Air fuel ratio sensor ECM |
| P0132 | One of the following conditions is met for 1 second or more (1 trip detection logic): The voltage of A1A+ is more than 4.7 V. The voltage of A1A- is more than 4.7 V. | |
| P0134 | Air fuel ratio sensor impedance is 450 ohms or more for 5 seconds or more. (1 trip detection logic) |
These DTCs are output when there is an open or short in the air fuel ratio sensor circuit, or if the air fuel ratio sensor output drops. To detect these problems, the voltage of the air fuel ratio sensor is monitored when turning the ignition switch to ON, and the admittance (admittance is an electrical term that indicates the ease of flow of current) is checked while driving. If the voltage of the air fuel ratio sensor is between 0.6 V and 4.5 V, it is considered normal. If the voltage is out of the specified range, or the admittance is less than the standard value, the ECM determines that there is a malfunction in the air fuel ratio sensor. If the same malfunction is detected in next driving cycle, the MIL is illuminated and a DTC is stored.
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 TWC (Three-Way Catalytic Converter) is used. For the most efficient use of the TWC, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric air fuel level. For the purpose of helping the ECM to deliver accurate air fuel ratio control, a Heated Oxygen (HO2) sensor is used.
The HO2 sensor is located behind the TWC, and detects the oxygen concentration in the exhaust gas. Since the sensor is integrated with the heater that heats the sensing portion, it is possible to detect the oxygen concentration even when the intake air volume is low (the exhaust gas temperature is low).
When the air fuel ratio becomes lean, the oxygen concentration in the exhaust gas is rich. The HO2 sensor informs the ECM that the post-TWC air fuel ratio is lean (low voltage, i.e. less than 0.45 V).
Conversely, when the air fuel ratio is richer than the stoichiometric air fuel level, the oxygen concentration in the exhaust gas becomes lean. The HO2 sensor informs the ECM that the post-TWC air fuel ratio is rich (high voltage, i.e. more than 0.45 V). The HO2 sensor has the property of changing its output voltage drastically when the air fuel ratio is close to the stoichiometric level.
The ECM uses the supplementary information from the HO2 sensor to determine whether the air fuel ratio after the TWC is rich or lean, and adjusts the fuel injection time accordingly. Thus, if the HO2 sensor is working improperly due to internal malfunctions, the ECM is unable to compensate for deviations in the primary air fuel ratio control.
Scheme 125
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0137 | Heated Oxygen (HO2) sensor voltage is less than 0.03 V. (2 trip detection logic) | Heated oxygen sensor circuit Heated oxygen sensor Gas leak from exhaust system |
| P0138 | Heated Oxygen (HO2) sensor voltage is 1.2 V or more for 2.5 seconds or more. (2 trip detection logic) | |
| P013A | The response rate for heated oxygen sensor voltage to change from 0.5 V (rich) to 0.2 V (lean) is slow for more than 0.491 seconds. (2 trip detection logic) | |
| P013B | The response rate for heated oxygen sensor voltage to change from 0.3 V (lean) to 0.5 V (rich) is slow for more than 4 seconds. (2 trip detection logic) | |
| P013E | Heated oxygen sensor voltage is slow in dropping to 0.5 V or less for more than 4 seconds. (2 trip detection logic) | |
| P013F | Heated oxygen sensor voltage is slow in increasing to 0.3 V or more for more than 120 seconds. (2 trip detection logic) | |
| P0140 | One of the following conditions is met for 90 seconds or more (2 trip detection logic): The minimum voltage of heated oxygen sensor does not drop below 0.15 V. The maximum voltage of heated oxygen sensor does not exceed 0.55 V. |
Scheme 126
- Abnormal Voltage Output of Heated Oxygen (HO2) Sensor (DTC P013B, P013F or P0140) If the sensor is not functioning properly, the voltage output variation is small. For example, when the HO2 sensor voltage does not decrease to less than 0.15 V and does not increase to more than 0.55 V, the ECM determines that the sensor voltage output is abnormal and stores DTC P013B, P013F or P0140.
- Open in Heated Oxygen (HO2) Sensor Circuit (DTC P0137) The ECM calculates the Oxygen Storage Capacity (OSC)* of the Three-Way Catalytic Converter (TWC) by forcibly regulating the air fuel ratio to become rich or lean. If the HO2 sensor has an open or short, or the voltage output of the sensor noticeably decreases, OSC indicates an extraordinarily high value. Even if the ECM attempts to continue regulating the air fuel ratio to become rich or lean, the HO2 sensor output does not change. When the target air fuel ratio is rich and the HO2 sensor voltage output is 0.03 V or less (lean), the ECM interprets this as an abnormally low sensor output voltage and stores DTC P0137. HINT: *: The TWC has the capability to store oxygen. The OSC and the emission purification capacity of the TWC are mutually related. The ECM determines whether the catalyst has deteriorated, based on the calculated OSC value. Refer to «DESCRIPTION»(ref-612372-S34922717302014042900000).
- Extremely High Output Voltage of Heated Oxygen (HO2) Sensor (DTC P0138) The ECM continuously monitors the HO2 sensor output voltage while the engine is running. DTC P0138 is stored if the HO2 sensor voltage output is more than 1.2 V.
- Abnormal Voltage Output of Heated Oxygen (HO2) Sensor During Fuel-cut (DTC P013A or P013E) The sensor output voltage drops to below 0.2 V (extremely lean status) immediately when the vehicle decelerates and fuel cut is operating. If the voltage does not drop to below 0.5 V for 4 seconds or more, or voltage does not drop from 0.5 V to 0.2 V, the ECM determines that the sensor response has deteriorated, illuminates the MIL and stores a DTC.
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 TWC (Three-Way Catalytic Converter) is used. For the most efficient use of the TWC, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric air fuel level. For the purpose of helping the ECM to deliver accurate air fuel ratio control, a Heated Oxygen (HO2) sensor is used.
The HO2 sensor is located behind the TWC, and detects the oxygen concentration in the exhaust gas. Since the sensor is integrated with the heater that heats the sensing portion, it is possible to detect the oxygen concentration even when the intake air volume is low (the exhaust gas temperature is low).
When the air fuel ratio becomes lean, the oxygen concentration in the exhaust gas is rich. The HO2 sensor informs the ECM that the post-TWC air fuel ratio is lean (low voltage, i.e. less than 0.45 V).
Conversely, when the air fuel ratio is richer than the stoichiometric air fuel level, the oxygen concentration in the exhaust gas becomes lean. The HO2 sensor informs the ECM that the post-TWC air fuel ratio is rich (high voltage, i.e. more than 0.45 V). The HO2 sensor has the property of changing its output voltage drastically when the air fuel ratio is close to the stoichiometric level.
The ECM uses the supplementary information from the HO2 sensor to determine whether the air fuel ratio after the TWC is rich or lean, and adjusts the fuel injection time accordingly. Thus, if the HO2 sensor is working improperly due to internal malfunctions, the ECM is unable to compensate for deviations in the primary air fuel ratio control.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0137 | Heated Oxygen (HO2) sensor voltage is less than 0.03 V. (2 trip detection logic) | Heated oxygen sensor circuit Heated oxygen sensor Gas leak from exhaust system |
| P0138 | Heated Oxygen (HO2) sensor voltage is 1.2 V or more for 2.5 seconds or more. (2 trip detection logic) | |
| P013A | The response rate for heated oxygen sensor voltage to change from 0.5 V (rich) to 0.2 V (lean) is slow for more than 0.491 seconds. (2 trip detection logic) | |
| P013B | The response rate for heated oxygen sensor voltage to change from 0.3 V (lean) to 0.5 V (rich) is slow for more than 4 seconds. (2 trip detection logic) | |
| P013E | Heated oxygen sensor voltage is slow in dropping to 0.5 V or less for more than 4 seconds. (2 trip detection logic) | |
| P013F | Heated oxygen sensor voltage is slow in increasing to 0.3 V or more for more than 120 seconds. (2 trip detection logic) | |
| P0140 | One of the following conditions is met for 200 seconds or more (2 trip detection logic): The minimum voltage of heated oxygen sensor does not drop below 0.15 V. The maximum voltage of heated oxygen sensor does not exceed 0.55 V. |
- Abnormal Voltage Output of Heated Oxygen (HO2) Sensor (DTC P013B, P013F or P0140) If the sensor is not functioning properly, the voltage output variation is small. For example, when the HO2 sensor voltage does not decrease to less than 0.15 V and does not increase to more than 0.55 V, the ECM determines that the sensor voltage output is abnormal and stores DTC P013B, P013F or P0140.
- Open in Heated Oxygen (HO2) Sensor Circuit (DTC P0137) The ECM calculates the Oxygen Storage Capacity (OSC)* of the Three-Way Catalytic Converter (TWC) by forcibly regulating the air fuel ratio to become rich or lean. If the HO2 sensor has an open or short, or the voltage output of the sensor noticeably decreases, OSC indicates an extraordinarily high value. Even if the ECM attempts to continue regulating the air fuel ratio to become rich or lean, the HO2 sensor output does not change. When the target air fuel ratio is rich and the HO2 sensor voltage output is 0.03 V or less (lean), the ECM interprets this as an abnormally low sensor output voltage and stores DTC P0137. HINT: *: The TWC has the capability to store oxygen. The OSC and the emission purification capacity of the TWC are mutually related. The ECM determines whether the catalyst has deteriorated, based on the calculated OSC value. Refer to «DESCRIPTION»(ref-612372-S41157175112014042900000).
- Extremely High Output Voltage of Heated Oxygen (HO2) Sensor (DTC P0138) The ECM continuously monitors the HO2 sensor output voltage while the engine is running. DTC P0138 is stored if the HO2 sensor voltage output is more than 1.2 V.
- Abnormal Voltage Output of Heated Oxygen (HO2) Sensor During Fuel-cut (DTC P013A or P013E) The sensor output voltage drops to below 0.2 V (extremely lean status) immediately when the vehicle decelerates and fuel cut is operating. If the voltage does not drop to below 0.5 V for 4 seconds or more, or voltage does not drop from 0.5 V to 0.2 V, the ECM determines that the sensor response has deteriorated, illuminates the MIL and stores a DTC.
Refer to DTC P2195. Refer to DESCRIPTION .
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P014C | The "Rich to Lean response rate deterioration level*" value is standard or less for 70 seconds. (2 trip detection logic) | Air fuel ratio sensor Air fuel ratio sensor heater ECM |
| P014D | The "Lean to Rich response rate deterioration level*" value is standard or more for 70 seconds. (2 trip detection logic) | |
| P015A | The "Rich to Lean delay level*" value is standard or more. (2 trip detection logic) | |
| P015B | The "Lean to Rich delay level*" value is standard or more. (2 trip detection logic) |
*: Calculated by ECM based on the air fuel ratio sensor output.
The ECM monitors the time required for the A/F sensor output to change from Rich to Lean, or from Lean to Rich. When "Rich to Lean response rate deterioration level" or "Rich to Lean delay level" exceeds the threshold, the ECM stores a DTC and illuminates the MIL.
