1996 TOYOTA RAV4 oxygen

− DIAGNOSTICSENGINE
DI−43
1996 RAV4 (RM447U)
INSPECTION PROCEDURE
1 Check for open and short in harness and connector between ECM and oxygen
sensor (See page IN−30).
NG Repair or replace harness or connector.
OK
2 Check for oxygen sensor date.
PREPARATION:
(a) Connect the OBDII scan tool or TOYOTA hand−held tester to the DLC 3.
(b) Warm up engine to normal operation temperature.
CHECK:
Read the oxygen sensor output voltage and short−term fuel trim.
RESULT:
PatternOxygen sensor output voltageShort−term fuel trim
1Lean condition (Changes at 0.55 V or less)Changes at about +20 %
2Rich condition (Changes at 0.35 V or more)Changes at about −20 %
3Except 1 and 2
1, 2 Check fuel trim system (See page DI−48).
3

A00292
O K N G N G N G
1 V
0.55 V
0.35 V
0 V
DI−44
− DIAGNOSTICSENGINE
1996 RAV4 (RM447U)
3 Check the output voltage of oxygen sensor during idling.
PREPARATION:
Warm up the oxygen sensor with the engine at 2,500 rpm for approx. 90 sec.
CHECK:
Use the OBDII scan tool or TOYOTA hand−held tester read the output voltage of the oxygen sensor during
idling.
OK:
Oxygen sensor output voltage:
Alternates repeatedly between approx. 0.35 V and approx. 0.55 V (See the following table.)
OK Perform confirmation driving pattern
(See page DI−42).
NG
Replace oxygen sensor.

− DIAGNOSTICSENGINE
DI−45
1996 RAV4 (RM447U)
DTC P0133 Oxygen Sensor Circuit Slow Response
(Bank 1 Sensor 1)
CIRCUIT DESCRIPTION
Refer to ”Insufficient Coolant Temp. for Closed Loop Fuel Control” on page DI−39.
DTC No.DTC Detecting ConditionTrouble Area
P0133
Response time for the oxygen sensor’s voltage output to
change from rich to lean, or from lean to rich, is 1 sec. or more
during idling after the engine is warmed up
(2 trip detection logic)
Oxygen sensor
HINT:
Sensor 1 refers to the sensor closer to the engine body.
INSPECTION PROCEDURE
1 Are there any other codes (besides DTC P0133) being output?
YES Go to relevant DTC chart.
NO
Replace oxygen sensor.
DI3ZL−01

DI−46
− DIAGNOSTICSENGINE
1996 RAV4 (RM447U)
DTC P0136 Oxygen Sensor Circuit Malfunction
(Bank 1 Sensor 2)
CIRCUIT DESCRIPTION
Refer to ”Insufficient Coolant Temp. for Closed Loop Fuel Control” on page DI−39.
DTC No.DTC Detecting ConditionTrouble Area
P0136
Voltage output of the oxygen sensor (bank 1 sensor 2)
remains at 0.4 V or more or 0.5 V or less when the vehicle is
driven at 40km/h (25 mph) or more after the engine is warmed
up
(2 trip detection logic)
Oxygen sensor
HINT:
Sensor 2 refers to the sensor farther away from the engine body.
WIRING DIAGRAM
Refer to page DI−39 for the WIRING DIAGRAM.
INSPECTION PROCEDURE
1 Are there any other codes (besides DTC P0136) being output?
YES Go to relevant DTC chart.
NO
2 Check for open and short in harness and connector between ECM and oxygen
sensor (See page IN−30).
NG Repair or replace harness or connector.
OK
DI3ZM−01

− DIAGNOSTICSENGINE
DI−47
1996 RAV4 (RM447U)
3 Check the output voltage of oxygen sensor (bank 1 sensor 2).
PREPARATION:
(a) Connect the OBDII scan tool or TOYOTA hand−held tester to the DLC 3.
(b) Warm up engine to normal operating temperature.
CHECK:
Read the output voltage of oxygen sensor (Bank 1 Sensor 2) when engine is suddenly raced.
HINT:
Perform quick racing to 4,000 rpm for 3 mins using accelerator pedal.
OK:
Oxygen sensor output voltage: Alternates from 0.4 V or less to 0.5 V or more.
OK Check that each connector is properly con-
nected.
NG
Replace oxygen sensor.

DI−48
− DIAGNOSTICSENGINE
1996 RAV4 (RM447U)
DTC P0171 System too Lean (Fuel Trim)
DTC P0172 System too Rich (Fuel Trim)
CIRCUIT DESCRIPTION
”Fuel trim” refers to the feedback compensation value compared against the basic injection time. Fuel trim
includes short−term fuel trim and long−term fuel trim.
”Short−term fuel trim” is the short−term fuel compensation used to maintain the air−fuel ration at its ideal
theoretical value. The signal from the oxygen sensor indicates whether the air−fuel ratio is RICH or LEAN
compared to the ideal theoretical value, triggering a reduction in fuel volume if the air−fuel ratio is rich, and
an increase in fuel volume if it is lean.
”Long−term fuel trim” is overall fuel compensation carried out long−term to compensate for continual devi-
ation of the short−term fuel trim from the central value due to individual engine differences, wear over time
and changes in the usage environment.
If both the short−term fuel trim and long−term fuel trim are LEAN or RICH beyond a certain value, it is de-
tected as a malfunction and the MIL lights up.
DTC No.DTC Detecting ConditionTrouble Area
P0171
When the air fuel ratio feedback is stable after engine warning
up, the fuel trim is considerably in error on the RICH side
(2 trip detection logic)
Fuel line pressure
Injector blockage
Oxygen sensor malfunction
Manifold absolute pressure sensor
Engine coolant temp. sensor
P0172
When the air fuel ratio feedback is stable after engine warning
up, the fuel trim is considerably in error on the LEAN side
(2 trip detection logic)
Fuel line pressure
Injector blockage, leak
Oxygen sensor malfunction
Manifold absolute pressure sensor
Engine coolant temp. sensor.
HINT:
When DTC P0171 is recorded, the actual air−fuel ratio is on the LEAN side. When DTC P0172 is re-
corded, the actual air−fuel ratio is on the RICH side.
If the vehicle runs out of fuel, the air−fuel ratio is LEAN and DTC P0171 is detected. The MIL then
comes on.
If the total of the short−term fuel trim value and long−term fuel trim value is within ±25 %, the system
is functioning normally.
INSPECTION PROCEDURE
1 Check air induction system (See page SF−1).
NG Repair or replace.
OK
DI3ZN−01

− DIAGNOSTICSENGINE
DI−49
1996 RAV4 (RM447U)
2 Check for oxygen sensor data.
PREPARATION:
(a) Connect the OBDII scan tool or TOYOTA hand−held tester to the DLC3.
(b) Warm up engine to normal operating temperature.
CHECK:
Read the oxygen sensor output voltage and short−term fuel trim.
RESULT:
PatternOxygen sensor output voltageShort−term fuel trim
1Lean condition (Changes at 0.55 V or less)Changes at about +20 %
2Rich condition (Changes at 0.35 V or more)Changes at about −20 %
3Except 1 and 2
3 Check for oxygen sensor
(See page DI−42).
1, 2
3 Check fuel pressure (See page SF−5).
NG Check and repair fuel pump, pressure regulator,
fuel pipe line and filter (See page SF−1).
OK
4 Check injector injection (See page SF−21).
NG Replace injector.
OK
5 Check manifold absolute pressure sensor and engine coolant temp. sensor
(See page DI−21, DI−29).
NG Repair or replace.
OK

FI7081
Waveform of oxygen sensor
before catalystNormal
catalystWaveform of oxygen sensor
after catalyst
− DIAGNOSTICSENGINE
DI−73
1996 RAV4 (RM447U)
DTC P0420 Catalyst System Efficiency Below Threshold
CIRCUIT DESCRIPTION
The ECM compares the waveform of the oxygen sensor located before the catalyst with the waveform of
the oxygen sensor located after the catalyst to determine whether or not catalyst performance has deterio-
rated.
Air−fuel ratio feedback compensation keeps the waveform of the oxygen sensor before the catalyst repeat-
edly changing back and forth from rich to lean.
If the catalyst is functioning normally, the waveform of the oxygen sensor after the catalyst switches back
and forth between rich and lean much more slowly than the waveform of the oxygen sensor before the cata-
lyst.
But when both wavaforms change at a similar rate, it indicates that catalyst performance has deteriorated.
DTC NoDTC Detecting ConditionTrouble Area
P0420
After the engine and the catalyst are warmed up, and while the
vehicle is driven within the set vehicle and engine speed range,
the waveforms of the oxygen sensors (bank 1 sensor 1 and
bank 1 sensor 2) have the same amplitude
(2 trip detection logic)
Front TWC (front catalyst) and TWC w/pipe (rear catalyst)
Oxygen sensor
DI3ZV−01