Engine Control (Sfi) System (Diagnostic Codes (P0300-P106A)) (Except Phv): Overview Toyota Prius III

Scheme 321

TEXT IN ILLUSTRATION

When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. High HC concentration levels can cause an increase in exhaust emission levels. Extremely high concentrations of HC can also cause increases in the three-way catalytic converter temperature, which may cause damage to the three-way catalytic converter. To prevent this increase in emissions and to limit the possibility of thermal damage, the ECM monitors the misfire rate. When the temperature of the three-way catalytic converter reaches the point of thermal degradation, the ECM blinks the MIL. To monitor misfires, the ECM uses both the Camshaft Position (CMP) sensor and the Crankshaft Position (CKP) sensor. The camshaft position sensor is used to identify any misfiring cylinders and the crankshaft position sensor is used to measure variations in the crankshaft rotation speed. Misfires are counted when the crankshaft rotation speed variations exceed predetermined thresholds. If the misfire count exceeds the threshold levels, and could cause emission control system performance deterioration, the ECM illuminates the MIL and sets a DTC.

When DTCs for misfiring cylinders are randomly set, but DTC P0300 is not set, it indicates that misfires have been detected in different cylinders at different times. DTC P0300 is only set when several misfiring cylinders are detected at the same time.

MONITOR DESCRIPTION

The ECM illuminates the MIL and sets a DTC when either one of the following conditions, which could cause emission control system performance deterioration, is detected (2 trip detection logic).

1. Within the first 1000 crankshaft revolutions of the engine starting, an excessive misfiring rate (approximately 20 to 50 misfires per 1000 crankshaft revolutions) occurs once.
2. An excessive misfiring rate (approximately 20 to 50 misfires per 1000 crankshaft revolutions) occurs a total of 4 times.

The ECM flashes the MIL and sets a DTC when either one of the following conditions, which could cause the three-way catalytic converter damage, is detected (2 trip detection logic).

HINT

If a catalyst damage misfire occurs, the monitor informs the driver by blinking the MIL (1 trip).

1. In every 200 crankshaft revolutions at a high engine speed, the threshold misfiring percentage is recorded once.
2. In every 200 crankshaft revolutions at a normal engine speed, the threshold misfiring percentage is recorded 3 times.

Misfire Monitor for Mexico Models

The ECM illuminates the MIL and sets a DTC when either one of the following conditions, which could cause emission deterioration, is detected (2 trip detection logic).

1. Within the first 1000 crankshaft revolutions of the engine starting, an excessive misfiring rate (approximately 1000 misfires per 1000 crankshaft revolutions) occurs once.
2. An excessive misfiring rate (approximately 500 misfires per 1000 crankshaft revolutions) occurs a total of 4 times.

The ECM flashes the MIL and sets a DTC when the following condition, which could cause the three-way catalytic converter damage, is detected (2 trip detection logic).

1. A catalyst damage misfire, which is monitored every 200 crankshaft revolutions, occurs 3 times.

DESCRIPTION

A flat type knock control sensor is used. Flat type knock control sensors (non-resonant type) have a structure that can detect vibrations over a wide band of frequencies: between approximately 6 kHz and 15 kHz.

Knock control sensors are fitted onto the engine block to detect engine knocking.

The knock control sensor contains a piezoelectric element which generates a voltage when it becomes deformed.

The voltage is generated when the engine block vibrates due to knocking. Occurrence of engine knocking can be suppressed by delaying the ignition timing.

HINT

When either DTC P0327 or P0328 is set, the ECM enters fail-safe mode. During fail-safe mode, the ignition timing is delayed to its maximum retardation. Fail-safe mode continues until the power switch is turned off.

Reference: Inspection using an oscilloscope

Scheme 322

The correct waveform is as shown.

If the output voltage transmitted by the knock sensor remains low or high for more than 1 second, the ECM interprets this as a malfunction in the sensor circuit, and sets a DTC.

The monitor for DTCs P0327 and P0328 begins to run when 5 seconds have elapsed since the engine was started.

If the malfunction is not repaired successfully, DTC P0327 or P0328 is set 5 seconds after the engine is next started.

The crankshaft position sensor system consists of a crankshaft position sensor plate and a pickup coil.

The sensor plate has 34 teeth and is installed on the crankshaft. The pickup coil is made of wound copper wire, an iron core and magnet. The sensor plate rotates and, as each tooth passes by the pickup coil, a pulse signal is created. The pickup coil generates 34 signals per engine revolution. Based on these signals, the ECM calculates the crankshaft position and engine speed. Using these calculations, the fuel injection time and ignition timing are controlled.

Scheme 323

1. Reference: Inspection using an oscilloscope. HINT: The correct waveform is as shown. G2+ is camshaft position sensor signals, and NE+ is the crankshaft position sensor signal. A failure of the ground for the shielding of the wiring may result in noisy waveforms. ECM Terminal Name Between NE+ and NE- Between G2+ and G2- Tester Range 5 V/DIV., 20 ms./DIV. Condition Idling with warm engine

If there is no signal from the crankshaft position sensor despite the engine rotating, the ECM interprets this as a malfunction of the sensor.

If the malfunction is not repaired successfully, a DTC is set 10 seconds after the engine is next started.

The camshaft position sensor for intake camshaft (G2 signal sensor) consists of a magnet and MR element.

The camshaft has a timing rotor for the camshaft position sensor. When the camshaft rotates, changes occur in the air gaps between the timing rotor and MR element, which affects the magnet. As a result, the resistance of the MRE material fluctuates. The camshaft position sensor converts the camshaft rotation data to pulse signals, and uses the pulse signals to determine the camshaft angle, which it sends to the ECM. Then the ECM uses this data to control fuel injection time and injection timing.

HINT

DTC P0340 indicates a malfunction relating to the camshaft position sensor circuit (the wire harness between the ECM and camshaft position sensor, and the camshaft position sensor itself).

Reference: Inspection using an oscilloscope. Refer to DESCRIPTION.

If no signal is transmitted by the camshaft position sensor despite the engine revolving, or the rotation of the camshaft and the crankshaft is not synchronized, the ECM interprets this as a malfunction of the sensor.

If the malfunction is not repaired successfully, the DTC is set 10 seconds after the engine is nest started.

HINT

1. These DTCs indicate malfunctions relating to the primary circuit.
2. If DTC P0351 is set, check the No. 1 ignition coil assembly circuit.
3. If DTC P0352 is set, check the No. 2 ignition coil assembly circuit.
4. If DTC P0353 is set, check the No. 3 ignition coil assembly circuit.
5. If DTC P0354 is set, check the No. 4 ignition coil assembly circuit.

A Direct Ignition System (DIS) is used on this vehicle.

The DIS is an ignition system in which each cylinder is ignited by it's own ignition coil assembly and spark plug. The secondary wiring of each ignition coil generates a powerful voltage which is applied directly to each spark plug. The spark passes from the center electrode of the spark plug to the ground electrode.

The ECM determines the ignition timing and transmits the ignition (IGT) signals to each cylinder. Using the IGT signal, the ECM turns the power transistor inside the igniter on and off. The power transistor, in turn, switches on and off the current to the primary coil. When the current to the primary coil is cut off, a powerful voltage is generated in the secondary coil. This voltage is applied to the spark plugs, causing them to spark inside the cylinders. As the ECM cuts the current to the primary coil, the igniter sends back an ignition confirmation (IGF) signal to the ECM, for each cylinder ignition.

Scheme 324

Scheme 325

1. Reference: Inspection using an oscilloscope.
2. While cranking or idling the engine, check the waveform between terminals IGT (1 to 4) and E1, and IGF and E1 of the ECM connector. ECM Terminal Name Between IGT (1 to 4) and E1 Between IGF and E1 Tester Range 2 V/DIV., 20 ms./DIV. Condition Idling

Scheme 326

If the ECM does not receive any IGF signals despite transmitting the IGT signal, it interprets this as a fault in the igniter and sets a DTC.

If the malfunction is not repaired successfully, a DTC is set 1 second after the engine is next started.

Based on the driving conditions, the ECM regulates the volume of exhaust gas that is recirculated to the engine's combustion chambers and thus lowers the combustion temperature to reduce NOx emissions. The ECM monitors signals such as engine speed, coolant temperature, electric load, and vehicle speed. When the EGR permission conditions are fulfilled, the ECM controls the opening of the EGR valve linearly through signals to the EGR step motor.

The ECM monitors the pressure inside the intake manifold while opening and closing the EGR valve during fuel cut operation. If there is no change in the manifold absolute pressure sensor value, the ECM interprets this as a malfunction in the EGR valve assembly, illuminates the MIL and stores the DTC (2 trip detection logic).

Refer to DTC P0401. Refer to DESCRIPTION.

HINT

DTC P0403 is set when the power switch is on (IG).

This DTC is designed to detect an open or short in the EGR valve assembly circuit.

Example

1. If the EGR1, EGR2, EGR3 or EGR4 terminal output voltage is excessively low, but the step motor is still operating, the ECM determines that there is a short in the EGR valve assembly circuit , and sets the DTC.
2. If the EGR1, EGR2, EGR3 or EGR4 terminal output voltage is excessively low, and the step motor is not operating, the ECM determines that there is an open in the EGR valve assembly circuit, and sets the DTC.

The ECM uses sensors mounted in front of and behind the three-way catalytic converter to monitor its efficiency.

The first sensor, the air fuel ratio sensor, sends pre-catalyst information to the ECM. The second sensor, the heated oxygen sensor, sends post-catalyst information to the ECM.

In order to detect any deterioration in the three-way catalytic converter, the ECM calculates the oxygen storage capacity of the three-way catalytic converter. This calculation is based on the voltage output of the heated oxygen sensor while performing active air fuel ratio control.

The oxygen storage capacity value is an indication of the oxygen storage capacity of the three-way catalytic converter. When the vehicle is being driven with a warm engine, active air fuel ratio control is performed for approximately 15 to 20 seconds. When it is performed, the ECM deliberately sets the air fuel ratio to lean or rich levels. If the cycle of the waveform for the heated oxygen sensor is long, the oxygen storage capacity is great. There is a direct correlation between the heated oxygen sensor and the oxygen storage capacity of the three-way catalytic converter.

The ECM uses the oxygen storage capacity value to determine the state of the three-way catalytic converter. If any deterioration has occurred, it illuminates the MIL and sets the DTC.

HINT

1. Sensor 1 refers to the sensor closest to the engine assembly.
2. Sensor 2 refers to the sensor farthest away from the engine assembly.

Scheme 327

TEXT IN ILLUSTRATION

The circuit description can be found in the EVAP (Evaporative Emission) System. Refer to DESCRIPTION.

5 hours*1 after the power switch is turned off, the leak detection pump creates negative pressure (vacuum) in the EVAP (Evaporative Emission) system. The ECM monitors for leaks and actuator malfunctions based on the EVAP pressure.

HINT

*1: If the engine coolant temperature is not below 35°C (95°F) 5 hours after the power switch is turned off, the monitor check starts 2 hours later. If it is still not below 35°C (95°F) 7 hours after the power switch is turned off, the monitor check starts 2.5 hours later.

*2: If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize.

Scheme 328

Scheme 329

The leak detection pump creates negative pressure through the reference orifice. When the system is normal, the EVAP pressure is in 724 to 752 mmHg* and saturated within a minute.

If not, the ECM interprets this as a malfunction. The ECM will illuminate the MIL and set DTC if this malfunction is detected in consecutive driving cycle.

*: Typical value

The circuit description can be found in the EVAP (Evaporative Emission) System. Refer to DESCRIPTION.

The 2 monitors, key-off and purge flow, are used to detect malfunctions relating to DTC P0441. The key-off monitor is initiated by the ECM internal timer, known as the soak timer, 5 hours*1 after the power switch is turned off. The purge flow monitor runs while the engine is running.

Scheme 330

Scheme 331

Scheme 332

1. KEY-OFF MONITOR 5 hours*1 after the power switch is turned off, the electric leak detection pump creates negative pressure (vacuum) in the EVAP (Evaporative Emission) system. The ECM monitors for leaks and actuator malfunctions based on the EVAP pressure. HINT: *1: If the engine coolant temperature is not below 35°C (95°F) 5 hours after the power switch is turned off, the monitor check starts 2 hours later. If it is still not below 35°C (95°F) 7 hours after the power switch is turned off, the monitor check starts 2.5 hours later. Sequence Operation Description Duration - ECM activation Activated by soak timer, 5, 7 or 9.5 hours after power switch turned off. - A Atmospheric pressure measurement Vent valve is turned off (vent) and EVAP system pressure is measured by ECM in order to register atmospheric pressure. If pressure in EVAP system is not between 70 kPa and 112 kPa (525 mmHg and 840 mmHg), ECM cancels EVAP system monitor. 60 seconds B First 0.02 inch leak pressure measurement In order to determine 0.02 inch leak pressure standard, leak detection pump creates negative pressure (vacuum) through 0.02 inch orifice and then ECM checks if leak detection pump and vent valve operate normally. 360 seconds C EVAP system pressure measurement Vent valve is turned on (closed) to shut EVAP system. Negative pressure (vacuum) is created in EVAP system, and EVAP system pressure is then measured. Write down measured value as it will be used in leak check. If EVAP pressure does not stabilize within 15 minutes, ECM cancels EVAP system monitor. 15 minutes*2 D Purge VSV monitor Purge VSV is opened and then EVAP system pressure is measured by ECM. A large increase indicates normal. 10 seconds E Second 0.02 inch leak pressure measurement After a second 0.02 inch leak pressure measurement, leak check is performed by comparing first and second 0.02 inch leak pressure standards. If stabilized system pressure is higher than second 0.02 inch leak pressure standard, ECM determines that EVAP system leaking. 60 seconds F Final check Atmospheric pressure is measured and then monitor result is recorded by ECM. - *2: If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize. Purge VSV stuck open In operation C, the leak detection pump creates negative pressure (vacuum) in the EVAP (Evaporative Emission) system. The EVAP system pressure is then measured by the ECM using the canister pressure sensor. If the stabilized system pressure is higher than [second 0.02 inch leak pressure standard x 0.2], the ECM interprets this as the purge VSV being stuck open. The ECM illuminates the MIL and sets the DTC (2 trip detection logic). HINT: *: DTC P0441 may be stored if the hose between the purge VSV and canister is disconnected during evaporative emission control system operation. Purge VSV stuck closed In operation D, the canister pressure sensor measures the EVAP (Evaporative Emission) system pressure. The pressure measurement for purge VSV monitor begins when the purge VSV is turned on (open) after the EVAP leak check. When the measured pressure indicates an increase of 0.3 kPa (2.25 mmHg) or more, the purge VSV is functioning normally. If the pressure does not increase, the ECM interprets this as the purge VSV being stuck closed. The ECM illuminates the MIL and sets the DTC (2 trip detection logic).
2. PURGE FLOW MONITOR The purge flow monitor consists of the 2 step monitors. The 1st monitor is conducted every time and the 2nd monitor is activated if necessary. The 1st monitor While the engine is running and the purge VSV is on (open), the ECM monitors the purge flow by measuring the EVAP pressure change. If negative pressure is not created, the ECM begins the 2nd monitor. The 2nd monitor The vent valve is turned on (closed) and the EVAP pressure is then measured. If the variation in the pressure is less than 0.5 kPa (3.75 mmHg), the ECM interprets this as the purge VSV being stuck closed, and illuminates the MIL and sets DTC P0441 (2 trip detection logic). Atmospheric pressure check: In order to ensure reliable malfunction detection, the variation between the atmospheric pressures, before and after conduction of the purge flow monitor, is measured by the ECM.

HINT

This DTC P0443 is applicable to Mexico models only.

To reduce hydrocarbons (HC) emissions, evaporated fuel from the fuel tank is routed through the canister to the intake manifold for combustion in the cylinders.

The ECM changes the duty signal to the purge VSV so that the intake quantity of hydrocarbons (HC) emissions is appropriate for the driving conditions (engine load, engine speed, vehicle speed, etc.) after the engine is warmed up.

Scheme 333

The description can be found in the EVAP (Evaporative Emission) System. Refer to DESCRIPTION.

Scheme 334

1. DTC P0451: Canister pressure sensor abnormal voltage fluctuation If the canister pressure sensor voltage output fluctuates rapidly for 10 seconds, the ECM stops the EVAP system monitor. The ECM interprets this as the canister pressure sensor voltage fluctuating, and stops the EVAP system monitor. The ECM then illuminates the MIL and sets the DTC. (Malfunction is detected by 2 trip detection logic.)
2. DTC P0452: Canister pressure sensor voltage low If the canister pressure sensor voltage output (pressure) is below 0.45 V (42.11 kPa (316 mmHg)), the ECM interprets this as an open or short circuit in the canister pressure sensor or its circuit, and stops the EVAP system monitor. The ECM then illuminates the MIL and sets the DTC (1 trip detection logic).
3. DTC P0453: Canister pressure sensor voltage high If the canister pressure sensor voltage output (pressure) is 4.9 V (123.761 kPa (928.5 mmHg) or more, the ECM interprets this as an open or short circuit in the canister pressure sensor or its circuit, and stops the EVAP system monitor. The ECM then illuminates the MIL and sets the DTC (1 trip detection logic).

The circuit description can be found in the EVAP (Evaporative Emission) System. Refer to DESCRIPTION.

5 hours*1 after the power switch is turned off, the leak detection pump creates negative pressure (vacuum) in the EVAP (Evaporative Emission) system. The ECM monitors for leaks and actuator malfunctions based on the EVAP pressure.

HINT

*1: If the engine coolant temperature is not below 35°C (95°F) 5 hours after the power switch is turned off, the monitor check starts 2 hours later. If it is still not below 35°C (95°F) 7 hours after the power switch is turned off, the monitor check starts 2.5 hours later.

*2: If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize.

Scheme 335

1. P0455: EVAP (Evaporative Emission) gross leak In operation C, the leak detection pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured. If the stabilized system pressure is higher than [second 0.02 inch leak pressure standard x 0.2] (near atmospheric pressure), the ECM determines that the EVAP system has a large leak, illuminates the MIL and sets the DTC (2 trip detection logic).
2. P0456: EVAP very small leak In operation C, the leak detection pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured. If the stabilized system pressure is higher than second 0.02 inch leak pressure standard, the ECM determines that the EVAP system has a small leak, illuminates the MIL and sets the DTC (2 trip detection logic).

The idle speed is controlled by the electronic throttle control system. The electronic throttle control system is comprised of: 1) the one valve type throttle body; 2) a throttle actuator, which operates the throttle valve; 3) a throttle position sensor, which detects the opening angle of the throttle valve; 4) an accelerator pedal position sensor, which detects the accelerator pedal position; and 5) the ECM, which controls the electronic throttle control system. Based on the target idle speed, the ECM controls the throttle actuator to provide the proper throttle valve opening angle.

The ECM monitors the idle speed and idle air flow volume to conduct Idle Speed Control (ISC). The ECM determines that the idle speed control system is malfunctioning if the following conditions apply

1. The learned idle air flow volume remains at the maximum or minimum volume for 5 seconds or more during a drive cycle.
2. After driving at a vehicle speed of 34.175 mph (55 km/h) or more, the actual engine idle speed varies from the target idle speed by less than -100 rpm or 150 rpm or more, 5 times or more during a driving cycle, the ECM illuminates the MIL and sets the DTC.

Scheme 336

This monitor will run when the engine is started at an engine coolant temperature of -10 to 50°C (14 to 122°F). The DTC can be set after the engine idles for 13 seconds (2 trip detection logic).

The DTC is designed to monitor the idle air control at cold start. When the engine is started at an engine coolant temperature of lower than 50°C (122°F), the ECM measures the accumulated mass air flow at idle. If it does not reach the specified level within 10 seconds, the ECM interprets this as a malfunction. The MIL is illuminated and a DTC is set when the malfunction is detected in consecutive driving cycles (2 trip detection logic).

The electronic throttle control system controls the idle speed. The electronic throttle control system operates the throttle actuator to open and close the throttle valve, and adjusts the intake air amount to achieve the target idle speed.

Note. When the negative battery terminal is disconnected during inspection or repairs, the idle speed control (ISC) learned values are cleared. Idle speed control learning needs to be performed before this DTC can be stored. To perform idle speed control learning, the engine must be warmed up by allowing it to idle for 5 minutes. For idle speed control learning to be successful, when the engine is started to warm it up, there must be at least 10 seconds of idling with the coolant temperature below 50°C (122°F) before allowing it to continue running for the 5 minute learning period.

HINT

The idle speed control learning is performed when the engine is warmed up and has been idling for 5 minutes.

Scheme 337

This monitor will run when the engine is started at -10 to 50°C (14 to 122°F) of the engine coolant temperature. The DTC can be set after the engine idles for 13 seconds or more (2 trip detection logic).

The DTC is designed to monitor the idle air control at cold start. When the engine is started at lower than 50°C (122°F) of the engine coolant temperature, the ECM measures the accumulated mass air flow at idle. If it does not reach the criteria within 10 seconds, the ECM interprets this as a malfunction. The MIL is illuminated and a DTC is set when the malfunction is detected in consecutive driving cycles (2 trip detection logic).

The electronic throttle control system controls the idle speed. The electrical throttle control system operates the throttle actuator to open and close the throttle valve, and adjusts the intake air amount to achieve the target idle speed.

Note. When the negative (-) battery terminal is disconnected during inspection or repairs, the idle speed control learned values are cleared. Idle speed control learning is performed when the engine has been warmed up and idled for 5 minutes because this DTC cannot be set after the idle speed control learned values are cleared.

Scheme 338

The battery supplies electricity to the ECM even when the power switch is off. This power allows the ECM to store data such as DTC history, freeze frame data and fuel trim values. If the battery voltage falls below a minimum level, the memory is cleared and the ECM determines that there is a malfunction in the power supply circuit. The next time the engine is started, the ECM illuminates the MIL and sets the DTC.

HINT

If DTC P0560 is set, the ECM does not store other DTCs or the data stored in the ECM may be partly cleared.

The ECM continuously monitors its internal memory status. This self-check ensures that the ECM is functioning properly. It is diagnosed by internal "mirroring" of the main CPU and sub CPU to detect Random Access Memory (RAM) errors. If outputs from these CPUs are different and deviate from the standards, the ECM will illuminate the MIL and set the DTC immediately.

The ECM continuously monitors its main and sub CPUs. This self-check ensures that the ECM is functioning properly. If outputs from the CPUs are different and deviate from the standards, the ECM will illuminate the MIL and set the DTC immediately.

The ECM continuously monitors its internal processors (CPUs) and heated oxygen sensor transistors. This self-check ensures that the ECM is functioning properly.

The main CPU and sub CPU of the ECM communicate with each other. The main CPU monitors the communications and WDC pulses from the sub CPU. When the signal malfunctions below deviate, the DTC is stored.

This DTC is output when a communication error occurs in the ECM.

The ECM monitors the input signals of the No. 1 throttle position sensor. When the ECM monitors the input signal of the No. 1 throttle position sensor, if the input signal and control signal deviate, the DTC is stored.

The ECM monitors its internal operation and stores this DTC when it detects an internal malfunction.

The ECM monitors its internal operation. If the internal operation is malfunctioning, the ECM illuminates the MIL and stores a DTC.

The ECM monitors the output voltage to the throttle actuator. This self-check ensures that the ECM is functioning properly. The output voltage is usually 0 V when the power switch is turned off. If the output voltage is higher than 7 V when the power switch is turned off, the ECM will illuminate the MIL and set the DTC the next time the power switch is turned on (IG).

HINT

*: Data List Name

Tis DTC is designed to detect a deviation in the output characteristics of a pressure sensor.

The pressure of the canister pressure sensor and manifold absolute pressure sensor is monitored 55 minutes after the power switch is turned off. If there is a difference in the pressures, the MIL is illuminated (2 trip detection logic).

HINT

Correct judgment may not be possible when the altitude is 13124 ft (4000 m) or more.

See also:
• ON-VEHICLE INSPECTION - Step 1
• ON-VEHICLE INSPECTION - Step 8
• INSPECTION
• ON-VEHICLE INSPECTION
• ON-VEHICLE INSPECTION - Step 2
• COMPONENTS