2001 TOYOTA PRIUS check engine

± DIAGNOSTICSENGINE
DI±53
2001 PRIUS (RM778U)
8 Are there DTC P0130 being output again?
YES Check for intermittent problems (See page
DI±3).
NO
Check and replace ECM.

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.

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).

A09300
Vehicle speed
40 km/h
(25 mph)
Idling(c)(d)
(e)
(a)
IG SW OFF
(b)
(e)
60 sec.
or more(d)
(d) Once
40 sec.
or moreTwice
40 sec.
or more11 times
40 sec.
or more
10 sec. 10 sec.(e)
10 sec.
± DIAGNOSTICSENGINE
DI±59
2001 PRIUS (RM778U)
DTC P0136 Oxygen Sensor Circuit Malfunction
(Bank 1 Sensor 2)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page DI±44.
DTC No.DTC Detecting ConditionTrouble Area
P0136
Voltage output of the heated oxygen sensor remains at 0.45 V
or more, or 0.55 V or less when the vehicle is driven at 40 km/h
(25 mph) or more after the engine is warmed up.
(2 trip detection logic).

Open or short in heated oxygen sensor circuit

Heated oxygen sensor
HINT:
Sensor 2 refers to the sensor farther away from the engine body.
WIRING DIAGRAM
Refer to DTC P0125 on page DI±44.
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 (Test) Mode (See page DI±3).
(c) Start the engine and let the engine idle for 60 seconds or more.
(d) Drive the vehicle at 40 km/h (25 mph) or more for 40 seconds or more.
(e) Let the engine idle for 10 seconds or more.
(f) Preform steps (d) to (e) 11 times.
HINT:

During performing the steps (d) to (e) 11 times, drive the vehicle at over 65 km and make the fuel cut
happen for over 3 sec.

If a malfunction exists, the MIL will be indicated on the multi information display during step (f).
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 hand±held tester, turn the ignition switch OFF after performing steps (c) to (f),
then perform steps (c) to (f) again.
DI6V6±02

DI±60
± DIAGNOSTICSENGINE
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 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±41).
NG Repair or replace harness or connector.
OK
3 Check output voltage of oxygen sensor.
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand±held tester to the DLC3.
(b) Warm up the engine to normal operating temp.
CHECK:
Read voltage output of oxygen sensor when engine suddenly raced.
HINT:
Perform a quick racing of 2,000 rpm or more 3 times by using the accelerator pedal.
OK:
Oxygen sensor output voltage: Alternates from 0.40 V or less to 0.50 V or more.
OK Check that each connector is properly con-
nected.
NG
Replace oxygen sensor.

DI±62
± DIAGNOSTICSENGINE
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 Check air induction system (See page SF±1).
NG Repair or replace.
OK
2 Check injector injection (See page SF±12).
NG Replace injector.
OK
3 Check mass air flow meter and engine coolant temp. sensor
(See page SF±22 and SF±49).
NG Repair or replace.
OK
4 Check for spark and ignition (See page IG±1).
NG Repair or replace.
OK

P18349
± DIAGNOSTICSENGINE
DI±63
2001 PRIUS (RM778U)
5 Check fuel pressure (See page SF±6).
NG Check and repair fuel pump and fuel pipe line.
OK
6 Check gas leakade on exhaust system.
NG Repair or replace.
OK
7 Check the output voltage of heated 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 heated oxygen sensor
during idling.
OK:
Oxygen sensor output voltage:
Alternates repeatedly between less than 0.4 V and more than 0.55 V (See the following table).
OK Go to step 9.
NG