PZEV Engine

DTC P2195 OXYGEN (A/F) SENSOR SIGNAL STUCK LEAN (BANK 1 SENSOR 1)
DTC P2196 OXYGEN (A/F) SENSOR SIGNAL STUCK RICH (BANK 1 SENSOR 1)

HINT: These DTCs are recorded when an air-fuel ratio (A/F) sensor circuit is not working properly.

DTC Detecting Condition:

Wiring Diagram:

CIRCUIT DESCRIPTION
This A/F sensor is the planar type. Compared to the conventional type, the sensor element and the heater portions have a narrow shape. The heater can directly conduct its heat to the zirconia element via the alumina, it helps to accelerate the sensor activation.

To obtain a high purification rate of the CO, HC and NOx components of the exhaust gas, a three-way catalytic converter is used. For the most efficient use of the three-way catalytic converter, the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric air-fuel ratio.

The A/F sensor has the characteristic that it provides output voltage* being approximately proportional to the existing air-fuel ratio. The A/F sensor output voltage* is used to provide feedback for the ECM to control the air-fuel ratio.

By the A/F sensor output, the ECM can determine the deviation amount from the stoichiometric air-fuel ratio and control the proper injection time immediately. If the A/F sensor is out of order, ECM is unable to perform accurate air-fuel ratio control.

The A/F sensor is equipped with a heater which heats the zirconia element via the alumina. The heater is controlled by the ECM. When the intake air volume is low (the temperature of the exhaust gas is low), the current flows to the heater to heat the sensor for the accurate oxygen concentration detection.

*: The voltage value changes at the inside of the ECM only.

HINT:
- After confirming DTCs P2195 and P2196 use the OBD II scan tool or the hand-held tester to confirm voltage output of A/F sensor (AFS B1 S1) from the "DIAGNOSIS/ENHANCED OBDII/DATA LIST/ALL".
- The A/F sensor's output voltage and the short-term fuel trim value can be read using the OBD II scan tool or the hand-held tester.
- The ECM controls the voltage of the AF1A+ and AF1A- terminals of the ECM to a fixed voltage. Therefore, it is impossible to confirm the A/F sensor output voltage without the OBD II scan tool or the hand-held tester.
- The OBD II scan tool (excluding hand-held tester) displays the one fifth of the A/F sensor output voltage which is displayed on the hand-held tester.





CONFIRMATION DRIVING PATTERN
(a) Connect the hand-held tester to the DLC3.
(b) Switch the hand-held tester from the normal mode to the check mode.
(c) Start the engine and warm it up with all the accessory switches OFF.
(d) Drive the vehicle at 38 to 75 mph (60 to 120 km/h) and engine speed at 1,400 to 3,200 rpm for 3 to 5 min.

HINT: If a malfunction exists, the MIL will illuminate during step (d).

NOTICE: If the conditions in this test are not strictly followed, detection of a malfunction will not occur. If you do not have a hand-held tester, turn the ignition switch OFF after performing steps (c) and (d), then perform step (d) again.

INSPECTION PROCEDURE

HINT:
Hand-held tester only:
Narrowing down the trouble area is possible by performing the "A/F CONTROL" ACTIVE TEST (A/F sensor, heated oxygen sensor or other trouble areas can be distinguished).
(a) Perform ACTIVE TEST using the hand-held tester (A/F CONTROL).

HINT: "A/F CONTROL" is an ACTIVE TEST which changes the injection volume -12.5 % or +25 %.

(1) Connect the hand-held tester to the DLC3 on the vehicle.
(2) Turn the ignition switch ON.
(3) Warm up the engine by running the engine at 2,500 rpm for approximately 90 sec.
(4) Select the item "DIAGNOSIS/ENHANCED OBD II/ACTIVE TEST/ A/F CONTROL".
(5) Perform "A/F CONTROL" with the engine in an idle condition (press the right or left button).

Result:
A/F sensor reacts in accordance with increase and decrease of injection volume:
+25% -> rich output: Less than 3.0 V
-12.5% -> lean output: More than 3.35 V

Heated oxygen sensor 2 reacts in accordance with increase and decrease of injection volume:
+25% -> rich output: More than 0.55 V
-12.5% -> lean output: Less than 0.4 V





NOTICE: There is a few seconds delay in the A/F sensor output and there is about 20 second delay in the heated oxygen sensor 2 output. The following A/F CONTROL procedure enables to technician to check and graph the voltage outputs of both the A/F Sensor and Heated Oxygen Sensor 2. For displaying the graph indication, enter "DIAGNOSIS/ENHANCED OBD II/ACTIVE TEST/ A/F CONTROL/USER DATA", then select "AFS B1S1 and O2S B1S2" by pressing "YES" button and push "ENTER" button before pressing "F4" button.

HINT:
- A low A/F sensor voltage could be caused by a rich air fuel mixture. Check for conditions that would cause the engine to run rich.
- A high A/F sensor voltage could be caused by a lean air fuel mixture. Check for conditions that would cause the engine to run lean.
- Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.

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