Toyota Tundra. Manual — part 1517
in fail-safe mode. Fail-safe mode continues until the ignition switch is turned off.
The ECM provides a pulse width modulated control circuit to adjust the current through the heater. The
A/F sensor heater circuit uses a relay on the +B side of the circuit.
Fig. 51: Air-Fuel Ratio Sensor - Circuit Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
DTC DETECTION CONDITION AND TROUBLE AREA REFERENCE CHART
HINT:
Bank 1 refers to the bank that includes No. 1 cylinder.
Bank 2 refers to the bank that does not include No. 1 cylinder.
Sensor 1 refers to the sensor closest to the engine assembly.
Sensor 2 refers to the sensor farthest away from the engine assembly.
MONITOR DESCRIPTION
The ECM uses information from the Air-Fuel Ratio (A/F) 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 (TWC) to purify
the exhaust gases.
DTC
DTC Detection Condition
Trouble Area
P0031
P0051
Air-Fuel Ratio (A/F) sensor heater
current less than 0.8 A (1 trip
detection logic)
Open in A/F sensor heater
circuit
A/F sensor heater (for Sensor
1)
Integration relay
ECM
P0032
P0052
Air-Fuel Ratio (A/F) sensor heater
current failure (1 trip detection
logic)
Short in A/F sensor heater
circuit
A/F sensor heater (for Sensor
1)
Integration relay
ECM
2009 Toyota Tundra
2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra
The A/F 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 A/F 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 A/F sensor becomes inaccurate. As a result, the ECM is
unable to regulate the air-fuel ratio properly.
When the current in the A/F sensor heater is outside the normal operating range, the ECM interprets this as a
malfunction in the sensor heater and sets a DTC.
Example:
The ECM stores DTC P0032 or P0052 when the current limiter port is failed. Conversely, when the heater
current is less than 0.8 A, DTC P0031 or P0051 is stored.
MONITOR STRATEGY
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
All:
TYPICAL ENABLING CONDITIONS - ALL
Related DTCs
P0031: A/F sensor heater (for Bank 1) open/short (Low electrical
current)
P0032: A/F sensor heater (for Bank 1) open/short (High electrical
current)
P0051: A/F sensor heater (for Bank 2) open/short (Low electrical
current)
P0052: A/F sensor heater (for Bank 2) open/short (High electrical
current)
Required Sensors/Components (Main) A/F sensor heater
Required Sensors/Components
(Related)
-
Frequency of Operation
Continuous
Duration
10 seconds
MIL Operation
Immediate
Sequence of Operation
None
2009 Toyota Tundra
2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra
TYPICAL MALFUNCTION THRESHOLDS
P0031 and P0051:
TYPICAL MALFUNCTION THRESHOLDS - P0031 AND P0051
P0032 and P0052:
TYPICAL MALFUNCTION THRESHOLDS - P0032 AND P0052
COMPONENT OPERATING RANGE
COMPONENT OPERATING RANGE
WIRING DIAGRAM
Refer to DTC P2195 .
INSPECTION PROCEDURE
HINT:
Read freeze frame data using the Techstream. Freeze frame data records the engine condition when
malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was
moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data
from the time the malfunction occurred.
1. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)
a. Disconnect the D33 or D34 A/F sensor connector.
Monitor runs whenever following DTCs not present
None
Battery voltage
Less than 20 V
Engine
Running
When either condition below is met:
Condition A or B
Condition A:
-
Heater output duty
More than 0%
Condition B:
-
When all conditions below are met:
-
Battery voltage
10.5 V or more
Time after engine start
10 seconds or more
A/F sensor heater duty-cycle ratio
50% or more
A/F sensor heater current
Less than 0.8 A
Hybrid IC high current limiter port
Fail
A/F sensor heater current
0.9 to 9.9 A
2009 Toyota Tundra
2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra
Fig. 52: Identifying Terminals Of D33 Or D34 A/F Sensor Connector
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
b. Measure the resistance according to the value(s) in the table below.
Standard resistance
RESISTANCE SPECIFIED CONDITION
NG: REPLACE AIR FUEL RATIO SENSOR (See REMOVAL )
OK: Go to next step.
2. CHECK TERMINAL VOLTAGE (+B OF A/F SENSOR)
a. Disconnect the D33 or D34 A/F sensor connector.
Tester Connection
Condition Specified Condition
1 (HA1A) - 2 (+B) 20°C (68°F)
1.8 to 3.4 ohms
1 (HA1A) - 4 (A1A-)
Always
10 kohms or higher
1 (HA2A) - 2 (+B) 20°C (68°F)
1.8 to 3.4 ohms
1 (HA2A) - 4 (A2A-)
Always
10 kohms or higher
2009 Toyota Tundra
2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra
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