2007 TOYOTA SIENNA Fuel System

ES–1202GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
• Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition
information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame
data can be helpful in determining whether the vehicle was running or stopped, whether the engine
was warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the
time of a malfunction.
(a) Disconnect the H14 heated oxygen (HO2) sensor
connector (Bank 1 Sensor 2) or H9 heated oxygen
sensor connector (Bank 2 Sensor 2).
(b) Measure the resistance according to the value(s) in the
table below.
Standard resistance:
Bank 1
Bank 2
(c) Reconnect the HO2 sensor connectors.
NG
OK
1INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)
A112643E03
Tester Connection Condition Specified Condition
HT (1) - +B (2) 20
C (68F) 11 to 16
HT (1) - E1 (4) Always 10 k or higher
Tester Connection Condition Specified Condition
HT (1) - +B (2) 20
C (68F) 11 to 16
HT (1) - E1 (4) Always 10 k or higher
REPLACE HEATED OXYGEN SENSOR

ES–1242GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
DESCRIPTION
The Mass Air Flow (MAF) 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 appropriate air-
fuel ratio. Inside the MAF 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, changing their resistance. To maintain a
constant current value, the ECM varies the voltage applied to these components in the MAF meter. The
voltage level is proportional to the air flow 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 provide 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 are set, the ECM enters fail-safe mode. During fail-safe mode, the ignition
timing is calculated by the ECM, according to the engine RPM and throttle valve position. Fail-safe mode
continues until a pass condition is detected.
HINT:
When any of these DTCs are set, check the air-flow rate by selecting the following menu items on an
intelligent tester: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / MAF.
DTC P0100 Mass or Volume Air Flow Circuit
DTC P0102 Mass or Volume Air Flow Circuit Low Input
DTC P0103 Mass or Volume Air Flow Circuit High Input
DTC No. DTC Detection Condition Trouble Area
P0100Open or short in Mass Air Flow (MAF) meter circuit for 3
seconds• Open or short in MAF meter circuit
• MAF meter
•ECM
P0102Open in Mass Air Flow (MAF) meter circuit for 3
seconds• Open in MAF meter circuit
• Short in ground circuit
• MAF meter
•ECM
P0103Short in Mass Air Flow (MAF) meter circuit for 3
seconds• Short in MAF meter circuit (+B circuit)
• MAF meter
•ECM
A140749E02

ES–1262GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition
information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data
can be helpful in determining whether the vehicle was running or stopped, whether the engine was
warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the time of
a malfunction.
(a) Connect the intelligent tester to the DLC3.
(b) Start the engine.
(c) Turn the tester on.
(d) Select the following menu items: DIAGNOSIS /
ENHANCED OBD II / DATA LIST / PRIMARY / MAF.
(e) Read the values displayed on the tester.
1READ VALUE OF INTELLIGENT TESTER (MASS AIR FLOW RATE)
A117876E09

ES–1302GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
DESCRIPTION
Refer to DTC P0100 (See page ES-116).
MONITOR DESCRIPTION
The MAF 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 MAF 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, changing their resistance. To maintain a
constant current value, the ECM varies the voltage applied to these components of the MAF meter. The
voltage level is proportional to the air flow through the sensor, and the ECM uses it to calculate the intake
air volume.
If there is a defect in the sensor, or an open or short in the circuit, the voltage level deviates from the
normal operating range. The ECM interprets this deviation as a malfunction in the MAF meter and sets the
DTC.
Example:
If the voltage is more than 2.2 V, or less than 0.73 V while idling, the ECM determines that there is a
malfunction in the MAF meter and sets the DTC.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
DTC P0101Mass or Volume Air Flow Circuit Range / Perfor-
mance Problem
DTC No. DTC Detection Condition Trouble Area
P01011. High voltage:
Conditions (a), (b) and (c) continue for more than
10 seconds (2 trip detection logic):
(a) Engine speed is less than 2000 rpm
(b) Engine coolant temperature is 70
C (158F) or
higher
(c) Voltage output of Mass Air Flow (MAF) meter is
more than 1.24 V (varies with Throttle Position [TP]
sensor voltage)
2. Low voltage:
Conditions (a) and (b) continue for more than 10
seconds (2 trip detection logic):
(a) Engine speed is more than 300 rpm
(b) Voltage output of MAF meter is less than 0.80 V
(varies with TP sensor voltage)MAF meter
Related DTCs P0101: Mass air flow meter rationality
Required Sensors / Components (Main) Mass air flow meter
Required Sensors / Components (Related)Crankshaft position sensor, engine coolant temperature sensor and throttle position
sensor
Frequency of Operation Continuous
Duration 10 times
MIL Operation 2 driving cycles
Sequence of Operation None
The monitor will run whenever these DTCs are not
presentP0115, P0116, P0117, P0118 (ECT Sensor), P0120, P0121, P0122, P0123, P0220,
P0222, P0223, P2135 (TP Sensor), P0125 (Insufficient ECT for Closed Loop),
P0335 (CKP Sensor), P0340 (CMP Sensor)
Throttle position (TP sensor voltage) 0.24 V or more

2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEMES–131
ESTYPICAL MALFUNCTION THRESHOLDS
WIRING DIAGRAM
Refer to DTC P0100 (See page ES-118).
INSPECTION PROCEDURE
HINT:
Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition
information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data
can be helpful in determining whether the vehicle was running or stopped, whether the engine was
warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the time of
a malfunction.
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the tester on.
(d) Select the following menu items: DIAGNOSIS /
ENHANCED OBD II / DTC INFO / CURRENT CODES.
(e) Read the DTCs.
Result
HINT:
If any DTCs other than P0101 are output, troubleshoot
those DTCs first.
B
A
Engine Running
Battery voltage 10.5 V or more
ECT 70
C (158F) or more
IAT sensor current OK
ECT sensor current OK
CKP sensor current OK
TP sensor current OK
FTP sensor OK
EVAP leak detection pump OK
EVAP vent valve OK
Averaged engine load Less than 0.80 %, or more than 1.24 %
1CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0101)
Display (DTC Output) Proceed to
P0101 and other DTCs A
P0101 B
REPLACE MASS AIR FLOW METER (See
page ES-504)
GO TO DTC CHART (See page ES-56)

ES–1322GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
DESCRIPTION
The Intake Air Temperature (IAT) sensor, mounted on the Mass Air Flow (MAF) meter, monitors the IAT.
The IAT sensor has a built-in thermistor with a resistance that varies according to the temperature of the
intake air. When the IAT 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 (see
Fig. 1).
The IAT sensor is powered by a 5 V applied from the THA terminal of the ECM, via resistor R.
Resistor R and the IAT sensor are connected in series. When the resistance value of the IAT sensor
changes, according to changes in the IAT, 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 any of DTCs P0110, P0112 and P0113 are set, the ECM enters fail-safe mode. During fail-safe
mode, the IAT is estimated to be 20
C (68F) by the ECM. Fail-safe mode continues until a pass condition
is detected.
DTC P0110 Intake Air Temperature Circuit
DTC P0112 Intake Air Temperature Circuit Low Input
DTC P0113 Intake Air Temperature Circuit High Input
DTC No. Proceed to DTC Detection Condition Trouble Area
P0110 Step 1Open or short in Intake Air Temperature (IAT)
sensor circuit for 0.5 seconds (1 trip detection
logic)• Open or short in IAT sensor circuit
• IAT sensor (built into MAF meter)
•ECM
P0112 Step 4Short in Intake Air Temperature (IAT) sensor
circuit for 0.5 seconds (1 trip detection logic)• Short in IAT sensor circuit
• IAT sensor (built into MAF meter)
•ECM
P0113 Step 2Open in Intake Air Temperature (IAT) sensor
circuit for 0.5 seconds (1 trip detection logic)• Open in IAT sensor circuit
• IAT sensor (built into MAF meter)
•ECM
A056276E06

ES–1342GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
• If other DTCs relating to different systems that have terminal E2 as the ground terminal are output
simultaneously, terminal E2 may have an open circuit.
• Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition
information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame
data can be helpful in determining whether the vehicle was running or stopped, whether the engine
was warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the
time of a malfunction.
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Turn the tester on.
(d) Select the following menu items: DIAGNOSIS /
ENHANCED OBD II / DATA LIST / PRIMARY / INTAKE
AIR.
(e) Read the value displayed on the tester.
Standard:
Same as actual Intake Air Temperature (IAT).
Result
HINT:
• If there is an open circuit, the intelligent tester
indicates -40
C (-40F).
• If there is a short circuit, the intelligent tester indicates
140
C (284F) or higher.
B
1READ VALUE OF INTELLIGENT TESTER (INTAKE AIR TEMPERATURE)
A136106E05
Temperature Displayed Proceed to
-40
C (-40F) A
140
C (284F) or higher B
Same as actual IAT C
Go to step 4

ES–1382GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES
DESCRIPTION
The Intake Air Temperature (IAT) sensor, mounted on the Mass Air Flow (MAF) meter, monitors the IAT.
The IAT sensor has a built-in thermistor with a resistance that varies according to the temperature of the
intake air. When the IAT becomes low, the resistance of the thermistor increases. When the temperature
becomes high, the resistance drops. These variations in resistance are transmitted to the ECM as voltage
changes (see Fig. 1).
The IAT sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor R.
Resistor R and the IAT sensor are connected in series. When the resistance value of the IAT sensor
changes according to changes in the IAT, 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.
MONITOR DESCRIPTION
The ECM performs OBD II monitoring based on the values from the intake air temperature sensor. If there
is no change in the sensor value, 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 the stuck intake air temperature
sensor value by performing monitoring after the ignition switch is turned off or the ignition is started (short
soak or long soak).
MONITOR STRATEGY
DTC P0111Intake Air Temperature Sensor Gradient Too
High
DTC No. DTC Detection Condition Trouble Area
P01111. The intake air temperature rise becomes larger,
from the previous trip warm-up to the following
trip.(2 trip detection logic)
2. When the change in the intake air temperature after
engine start is less than the threshold value.Mass air flow meter assembly
Related DTCsP0111: Intake air temperature sensor rationality (After engine stop)
P0111: Intake air temperature sensor rationality (After cold engine
start)
A067628E13