O2 sensor TOYOTA PRIUS 2001 Service Repair Manual

DI±46
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
HINT:

If the vehicle run out of fuel, the air±fuel ratio is LEAN and DTC P0125 will be recorded .
The MIL then comes on.

Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame
records the engine conditions when the malfunction is detected, when troubleshooting it is useful for
determining whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel
ratio lean or rich, etc at the time of the malfunction.

There is a possibility that P0125 is detected because of abnormal fuel system, so, when P0125 is mem-
orized, check P0171 and P0172 even if P0171 and P0172 are memorized.
1 Are there any other codes (besides DTC P0125) being output ?
YES Go to relevant DTC chart.
NO
2 Connect the OBD II scan tool or TOYOTA hand±held tester and read value for
voltage output of oxygen sensor (bank 1 sensor 1).
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand±held tester to the DLC3.
(b) Warm up engine to normal operating temp (above 75°C).
CHECK:
Read voltage output of the oxygen sensor (bank 1 sensor 1) when engine is suddenly raced.
HINT:
Perform quick racing to 4,000 rpm 3 times using accelerator pedal.
OK:
Both oxygen sensor (bank 1 sensor 1) output a RICH signal (0.45 V or more) at least once.
OK Go to step 9.
NG
3 Check for open and short in harness and connector between ECM and oxygen
sensor (bank 1 sensor 1) (See page IN±41).
NG Repair or replace harness or connector.
OK

DI±48
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
Replace oxygen sensor (bank 1 sensor 1).
9 Perform confirmation driving pattern (See page DI±50).
Go
10 Is there DTC P0125 being output again?
YES Check and replace ECM.
NO
11 Did vehicle runs out of fuel in the past?
NO Check for intermittent problems
(See page DI±3).
YES
DTC P0125 is caused by running out of fuel.

FI7130A14461
Vehicle
speed
Constant
speed
Start
online(c)(d)
IG SW
OFF30 sec. 36 sec.Time
(a) (b)
DI±50
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
DTC P0130 Oxygen Sensor Circuit Malfunction
(Bank 1 Sensor 1)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page DI±44.
DTC No.DTC Detecting ConditionTrouble Area
P0130
Voltage output of oxygen sensor remains at 0.42 V or more, or
0.48 V or less, during idling after the engine is warmed up (2
trip detection logic)

Open or short in heated oxygen sensor circuit

Heated oxygen sensor

Air induction system

Fuel pressure

Injector

ECM
HINT:
Sensor 1 refers to the sensor closer to the engine body.
The oxygen sensor's output voltage and the short-term fuel trim value can be read using the OBD II scan
tool or TOYOTA hand-held tester.
WIRING DIAGRAM
Refer to DTC P0125 on page DI±44.
CONFIRMATION DRIVING PATTERN
(a) Connect the TOYOTA hand±held tester to the DLC3.
(b) Switch the TOYOTA hand±held tester from normal mode to check mode (See page DI±3).
(c) Start the engine and pass for 30 sec. or more.
(d) Drive the vehicle at constant speed for 36 sec. or more.
HINT:
If a malfunction exists, the MIL will light up during step (d).
NOTICE:
If the conditions in this test are not strictly followed, detection of the malfunction will not be possible.
If you do not have a TOYOTA hand±held tester, turn the ignition switch OFF after performing steps
(c) to (d), then perform steps (c) to (d) again.
DI6V3±02

P18349
0.48 V
0.42 V
± DIAGNOSTICSENGINE
DI±51
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
HINT:
Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame records
the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel ratio lean or rich, etc.
at the time of the malfunction.
1 Are there any other codes (besides DTC P0130) being output?
YES Go to relevant DTC chart.
NO
2 Check the output voltage of oxygen sensor during idling.
PREPARATION:
Warm up the oxygen sensor the engine at 2,500 rpm for approx. 90 sec.
CHECK:
Use the OBD II 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 less than 0.42 V and more than 0.48 V (See the Following table).
OK Go to step 7.
NG

DI±52
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
3 Check for open and short in harness and connector between ECM and oxygen
sensor (bank 1 sensor 1) (See page IN±30).
NG Repair or replace harness or connector.
OK
4 Check air induction system (See page SF±1).
NG Repair or replace induction system.
OK
5 Check fuel pressure (See page SF±6).
NG Check and repair fuel pump, fuel pipe line and
filter (See page SF±1).
OK
6 Check injector injection (See page SF±12).
NG Replace injector.
OK
Replace oxygen sensor (bank 1 sensor 1).
7 Perform confirmation driving pattern (See page DI±50).
Go

DI±54
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
DTC P0133 Oxygen Sensor Circuit Slow
Responce (Bank 1 Sensor 1)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page DI±44.
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 0.4 sec. or
more during constant vehicle speed after the engine is warmed
up
(2 trip detection logic)
Open or short in heated oxygen sensor circuit

Heated oxygen sensor

Air induction system

Fuel pressure

Injector

ECM
HINT:
Sensor 1 refers to the sensor closer to the engine body.
INSPECTION PROCEDURE
HINT:
Read freeze frame data using TOYOTA hand±held tester or OBD II scantool. Because freeze frame records
the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel ratio lean or rich, etc.
at the time of the malfunction.
1 Are there any other codes (besides DTC P0133) being output?
YES Go to relevant DTC chart.
NO
DI6V4±02

P18349
0.48 V
0.42 V
± DIAGNOSTICSENGINE
DI±55
2001 PRIUS (RM778U)
2 Check the output voltage of heated oxygen sensor during idling.
PREPARATION:
Warm up the heated oxygen sensor the engine at 2,500 rpm for approx. 90 sec.
CHECK:
Use the OBD II scan tool or TOYOTA hand±held tester read the output voltage of the heated oxygen sensor
during idling.
OK:
Oxygen sensor output voltage:
Alternates repeatedly between less than 0.42 V and more than 0.48 V (See the Following table).
OK Go to step 7.
NG
3 Check for open and short in harness and connector between ECM and heated
oxygen sensor (bank 1 sensor 1) (See page IN±30).
NG Repair or replace harness or connector.
OK
4 Check air induction system (See page SF±1).
NG Repair or replace induction system.
OK

DI±56
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
5 Check fuel pressure (See page SF±6).
NG Check and repair fuel pump and fuel pipe line
(See page SF±1).
OK
6 Check injector injection (See page SF±12).
NG Replace injector.
OK
Replace oxygen sensor (bank 1 sensor 1).
7 Perform confirmation driving pattern (See page DI±50).
Go
8 Are there DTC P0133 being output again?
YES Check for intermittent problems
(See page DI±3).
NO
Check and replace ECM.

± DIAGNOSTICSENGINE
DI±57
2001 PRIUS (RM778U)
DTC P0135 Heated Oxygen Sensor Heater Circuit
Malfunction (Bank1 Sensor1)
DTC P0141 Heated Oxygen Sensor Heated Circuit
Malfunction (Bank1 Sensor2)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page DI±44.
DTC No.DTC Detecting ConditionTrouble Area
P0135
When the heater operates, heater current exceeds 2 A
(2 trip detection logic)
Open or short in heater circuit of heated oxygen sensor
Htd htP0135
P0141Heater current of 0.2 A or less when the heater operates
(2 trip detection logic)
Heated oxygen sensor heater

ECM
HINT:

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

Sensor 1 refers to the sensor closer to the engine body.

Sensor 2 refers to the sensor farther away from the engine body.
WIRING DIAGRAM
Refer to DTC P0125 on page DI±44.
INSPECTION PROCEDURE
HINT:
Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame records
the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel ratio lean or rich, etc.
at the time of the malfunction.
DI6V5±02

A13626
ON
HT1A
(+) (±) HT1B
DI±58
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
1 Check voltage between terminals HT1A, HT1B of ECM connectors and body
ground.
PREPARATION:
(a) Remove the ECM with connector still connected (See
page SF±62).
(b) Turn the ignition switch ON.
CHECK:
Measure voltage between terminals HT1A, HT1B of ECM con-
nectors and body ground.
HINT:

Connect terminal HT1A to bank 1 sensor 1.

Connect terminal HT1B to bank 1 sensor 2.
OK:
Voltage: 9 ± 14 V
OK Check and replace ECM (See page IN±41).
NG
2 Check resistance of heated oxygen sensor heater (See page SF±58).
NG Replace heated oxygen sensor.
OK
Check and repair harness or connector between EFI relay (Marking: EFI), heated oxygen sensor
and ECM (See page IN±41).