Toyota Tundra. Manual — part 1606

Fig. 234: Identifying A/F Sensor With Voltage Graph
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

DTC DETECTION CONDITION AND TROUBLE AREA REFERENCE CHART

DTC

DTC Detection Condition

Trouble Area

Conditions (a) and (b) continue for
5 seconds or more (2 trip detection



Open or short in A/F sensor
(for Sensor 1) circuit



A/F sensor (for Sensor 1)



A/F sensor heater (for Sensor

2009 Toyota Tundra

2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra

HINT:



DTCs P2195 and P2196 indicate malfunctions related to bank 1 A/F sensor circuit.



DTCs P2197 and P2198 indicate malfunctions related to bank 2 A/F sensor circuit.



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



Bank 2 refers to the bank that includes No. 2 cylinder.



When either of these DTCs is set, check the A/F sensor output voltage by entering the following menus:
Powertrain/Engine and ECT/Data List/A/F Control System/AFS Voltage B1 S1 or AFS Voltage B2 S1.



Short-term fuel trim values can also be read using the Techstream.



The ECM regulates the voltages at the A1A and A1 A- or A2A and A2A- terminals of the ECM to a

P2195
P2197

logic):

a. A/F sensor voltage more

than 3.8 V

b. Heated Oxygen (HO2)

sensor voltage 0.21 V or
more

1)



Integration relay



A/F sensor heater and
integration relay circuits



Air induction system



Fuel pressure



Injector



ECM

While fuel-cut operation
performed (during vehicle
deceleration), A/F sensor current
3.6 mA or more for 3 seconds (2
trip detection logic)



A/F sensor



ECM

P2196
P2198

Conditions (a) and (b) continue for
5 seconds or more (2 trip detection
logic):

a. A/F sensor voltage less than

2.8 V

b. HO2 sensor voltage less

than 0. 9 V



Open or short in A/F sensor
(for Sensor 1) circuit



A/F sensor (for Sensor 1)



A/F sensor heater (for Sensor
1)



Integration relay



A/F sensor heater and
integration relay circuits



Air induction system



Fuel pressure



Injector



ECM

While fuel-cut operation
performed (during vehicle
deceleration), A/F sensor current
less than 0.78 mA for 3 seconds (2
trip detection logic)



A/F sensor



ECM

2009 Toyota Tundra

2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra

constant level. Therefore, the A/F sensor output voltage cannot be confirmed without using the
Techstream.



If the A/F sensor is malfunctioning, the ECM sets the DTC P2195, P2196, P2197 or P2198.

MONITOR DESCRIPTION

Sensor voltage detection monitor

Under the air-fuel ratio feedback control, if the A/F sensor output voltage indicates rich or lean for a certain
period of time, the ECM determines that there is a malfunction in the A/F sensor. The ECM illuminates the MIL
and stores a DTC.

Example:

If the A/F sensor output voltage is less than 2.8 V (very rich condition) for 5 seconds, despite the rear HO2
sensor output voltage being less than 0.59 V, the ECM stores DTC P2196 or P2198. Alternatively, if the A/F
sensor output voltage is more than 3.8 V (very lean condition) for 5 seconds despite the rear HO2 sensor output
voltage being 0.21 V or more, DTC P2195 or P2197 is stored.

Sensor current detection monitor

A rich air-fuel mixture causes a low A/F sensor current, and a lean air-fuel mixture causes a high A/F sensor
current. Therefore, the sensor output becomes low during acceleration, and it becomes high during deceleration
with the throttle valve fully closed. The ECM monitors the A/F sensor current during fuel-cut and detects any
abnormal current values.

If the A/F sensor output is 3.6 mA or more for more than 3 seconds of cumulative time, the ECM interprets this
as a malfunction in the A/F sensor and stores DTC P2195 or P2197 (high-side stuck). If the A/F sensor output is
less than 0.78 mA for more than 3 seconds of cumulative time, the ECM stores DTC P2196 or P2198 (low-side
stuck).

2009 Toyota Tundra

2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra

Fig. 235: Monitoring Of A/F Sensor Current
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

MONITOR STRATEGY

MONITOR STRATEGY

Related DTCs

P2195: A/F sensor signal stuck lean (Bank 1)
P2196: A/F sensor signal stuck rich (Bank 1)
P2197: A/F sensor signal stuck lean (Bank 2)
P2198: A/F sensor signal stuck rich (Bank 2)

2009 Toyota Tundra

2009 ENGINE PERFORMANCE Engine Control System (3UR-FBE) - Tundra