Toyota Tundra. Manual — part 1335

Result

RESULT REFERENCE

B : REPLACE ECM (See REMOVAL )

A : CHECK FOR INTERMITTENT PROBLEMS (See CHECK FOR INTERMITTENT
PROBLEMS )

DTC P0037 OXYGEN SENSOR HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 2); DTC
P0038 OXYGEN SENSOR HEATER CONTROL CIRCUIT HIGH (BANK 1 SENSOR 2); DTC P0057
OXYGEN SENSOR HEATER CONTROL CIRCUIT LOW (BANK 2 SENSOR 2); DTC P0058
OXYGEN SENSOR HEATER CONTROL CIRCUIT HIGH (BANK 2 SENSOR 2); DTC P0141
OXYGEN SENSOR HEATER CIRCUIT MALFUNCTION (BANK 1 SENSOR 2); DTC P0161
OXYGEN SENSOR HEATER CIRCUIT MALFUNCTION (BANK 2 SENSOR 2)

DESCRIPTION

Refer to DTC P0136 .

HINT:



When any of these DTCs are set, the ECM enters fail-safe mode. The ECM turns off the Heated Oxygen
(HO2) Sensor heater 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
HO2 sensor heater circuit uses a relay on the +B side of the circuit.

Result

Proceed To

No DTC is output

A

P0031, P0032, P0051 or P0052 is output

B

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

Fig. 49: DTC P0037 Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2) - System Diagram

DTC DETECTION CONDITION AND TROUBLE AREA

HINT:



For Bank 1 refers to the bank that includes No. 1 cylinder.



For 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 sensing portion of the Heated Oxygen (HO2) 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.

Heated oxygen sensor heater range check (P0037, P0038, P0057 and P0058):

The ECM monitors the current applied to the O2 sensor heater to check the heater for malfunctions. If the

DTC

Code

DTC Detection Condition

Trouble Area

P0037
P0057

Heated Oxygen (HO2) sensor heater current less than 0.3
A (1 trip detection logic)



Open in HO2 sensor heater
circuit



HO2 sensor heater (for sensor
2)



Integration relay (EFI)



ECM

P0038
P0058

Heated Oxygen (HO2) sensor heater current more than 2
A (1 trip detection logic)



Short in HO2 sensor heater
circuit



HO2 sensor heater (for sensor
2)



Integration relay (EFI)



ECM

P0141
P0161

Cumulative heater resistance correction value exceeds
threshold (2 trip detection logic)



Open or short in HO2 sensor
heater circuit



HO2 sensor heater (for sensor
2)



Integration relay (EFI)



ECM

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

current is below the threshold value, the ECM determines that there is an open circuit in the heater. If the
current is above the threshold value, the ECM determines that there is a short circuit in the heater. The ECM
constantly monitors the current applied to the heater. If the ECM detects an open or short circuit, the ECM turns
the MIL on and sets a DTC.

If a malfunction is detected, the ECM cuts off the current applied to the heater.

Example:

The ECM sets DTC P0038 or P0058 when the current in the HO2 sensor heater is more than 2 A. Conversely,
when the heater current is less than 0.3 A, DTC P0037 or P0057 is set.

Heated oxygen sensor heater performance (P0141 and P0161):

After the accumulated heater ON time exceeds 100 seconds, the ECM calculates the heater resistance using the
battery voltage and the current applied to the heater.

If the resistance is above the threshold value, the ECM determines that there is a malfunction in the HO2 sensor
heater and set DTC P0141 or P0161.

MONITOR STRATEGY

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

Related DTCs

P0037: Heated oxygen sensor heater (bank 1) range check (Low
electrical current)
P0038: Heated oxygen sensor heater (bank 1) range check (High
electrical current)
P0057: Heated oxygen sensor heater (bank 2) range check (Low
electrical current)
P0058: Heated oxygen sensor heater (bank 2) range check (High
electrical current)
P0141: Heated oxygen sensor heater performance (bank 1)
P0161: Heated oxygen sensor heater performance (bank 2)

Required Sensors/Components
(Main)

Heated oxygen sensor heater

Required Sensors/Components
(Related)

-

Frequency of Operation

Continuous: P0037, P0038, P0057 and P0058
Once per driving cycle: P0141 and P0161

Duration

2 second: P0037, P0038, P0057 and P0058
10 seconds: P0141 and P0161

MIL Operation

Immediate: P0037, P0038, P0057 and P0058 2 driving cycles:
P0141 and P0161

Sequence of Operation

None

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

All:

TYPICAL ENABLING CONDITIONS - ALL

P0037 and P0057:

TYPICAL ENABLING CONDITIONS - P0037 AND P0057

P0038 and P0058:

TYPICAL ENABLING CONDITIONS - P0038 AND P0058

P0141 or P0161 (Heater performance monitor check):

TYPICAL ENABLING CONDITIONS - P0141 OR P0161 (HEATER PERFORMANCE MONITOR
CHECK)

TYPICAL MALFUNCTION THRESHOLDS

P0037 and P0057:

TYPICAL MALFUNCTION THRESHOLDS - P0037 AND P0057

P0038 and P0058:

TYPICAL MALFUNCTION THRESHOLDS - P0038 AND P0058

P0141 or P0161 (Heater performance monitor check):

TYPICAL MALFUNCTION THRESHOLDS - P0141 OR P0161 (HEATER PERFORMANCE
MONITOR CHECK)

COMPONENT OPERATING RANGE

Monitor runs whenever following DTCs not present

None

Battery voltage

10.5 to 20 V

Battery voltage

10.5 to 20 V

All of following conditions met:

-

Battery voltage

10.5 V or higher

Fuel cut

OFF

Time after fuel cut ON to OFF

30 seconds or more

Accumulated heater ON time

100 seconds or more

Heater current

Less than 0.3 A

Heater current

Higher than 2 A

Accumulated heater resistance Varies with sensor element temperature (Example: More than 23 ohms)

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra