2003 TOYOTA TACOMA (RM1002U)
A/F Sensor Circuit Slow Response
(Bank 1 Sensor 1)
Refer to DTC P2195 and P2196 on page DI–421.
DTC Detection Condition
In condition (a), (b) and (c), when the A/F sensor output
voltage change value is below the regular value against the
fuel trim change value, the ECM judges that A/F sensor
circuit has slow response: (2 trip detection logic)
(a) After engine is warmed up
(b) During vehicle driving at engine speed 1,400 rpm or
(c) Vehicle speed 60 km/h (38 mph) or more
Open or short in A/F sensor circuit
A/F sensor heater
EFI main relay
Air induction system
Refer to DTC P0134 on page DI–278.
Hand–held tester only:
The narrowing down the trouble area is possible by performing ACTIVE TEST of the following ”A/F CON-
TROL” (A/F sensor, heated oxygen sensor or another can be distinguished).
Perform ACTIVE TEST by hand–held tester (A/F CONTROL).
”A/F CONTROL” is an ACTIVE TEST which change the injection volume to –12.5 % or +25 %.
Connect the hand–held tester to the DLC3 on the vehicle.
Turn the ignition switch ON.
(3) Warm up the engine with the engine speed at 2,500 rpm for approx. 90 sec.
Select the item ”DIAGNOSIS/ENHANCED OBD II/ACTIVE TEST/ A/F CONTROL”.
Perform ”A/F CONTROL” when idle condition (press the ← or → button).
A/F sensor reacts in synchronizing 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 reacts in synchronizing with increase and decrease of injection volume
(+25 % → rich output: More than 0.55 V, –12.5 % → lean output: Less than 0.4 V)
However, there is a few second delay in the A/F sensor output. And there is about 20 seconds delay
in the heated oxygen sensor.
Output voltage of A/F sensor