2000 TOYOTA CAMRY O2 sensor

DI±272
± DIAGNOSTICSENGINE (1MZ±FE)
507 Author: Date:
DTC P0171 System too Lean (Fuel Trim)
(Except California Spec.)
DTC P0172 System too Rich (Fuel Trim)
(Except California Spec.)
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 ratio at its ideal
theoretical value. The signal from the heated 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 deviation
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
detected as a malfunction and the MIL lights up.
DTC No.DTC Detecting ConditionTrouble Area
P0171
When air fuel ratio feedback is stable after engine warming up,
fuel trim is considerably in error on RICH side
(2 trip detection logic)

Air intake (hose loose)

Fuel line pressure

Injector blockage

Heated oxygen sensors (bank 1, 2 sensor 1) malfunction

Mass air flow meter

Engine coolant temp. sensor

Gas leakage on exhaust system
P0172
When air fuel ratio feedback is stable after engine warming up,
fuel trim is considerably in error on LEAN side
(2 trip detection logic)

Fuel line pressure

Injector leak, blockage

Heated oxygen sensors (bank 1, 2 sensor 1) malfunction

Mass air flow meter

Engine coolant temp. sensor

Gas leakage on exhaust system
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 recorded. The MIL then
comes on.

If the total of the short±term fuel trim value and long±term fuel trim value is within + 35 % (80°C (176°F)
or more), the system is functioning normally.
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.
DI4DR±01

± DIAGNOSTICSENGINE (1MZ±FE)
DI±273
508 Author: Date:
1 Check air induction system (See page SF±1).
NG Repair or replace.
OK
2 Check injector injection (See page SF±21).
NG Replace injector.
OK
3 Check mass air flow meter and engine coolant temp. sensor
(See pages SF±35 and SF±63).
NG Repair or replace.
OK
4 Check for spark and ignition (See page IG±1).
NG Repair or replace.
OK
5 Check fuel pressure (See page SF±6).
NG Check and repair fuel pump, pressure regulator,
fuel pipe line and filter.
OK

P18349
DI±274
± DIAGNOSTICSENGINE (1MZ±FE)
509 Author: Date:
6 Check gas leakage on exhaust system.
NG Repair or replace.
OK
7 Check the output voltage of heated oxygen sensors (bank1, 2 sensor1) during
idling.
PREPARATION:
Warm up the heated oxygen sensors (bank1, 2 sensor1) the engine at 2,500 rpm for approx. 90 sec.
CHECK:
Use the OBDII scan tool or TOYOTA hand±held tester to read the output voltage of the heated oxygen sen-
sors (bank1, 2 sensor1) during idling.
OK:
Heated oxygen sensors (bank1, 2 sensor1) 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

± DIAGNOSTICSENGINE (1MZ±FE)
DI±275
510 Author: Date:
8 Check for open and short in harness and connector between ECM and heated
oxygen sensors (bank1, 2 sensor1) (See page SF±71).
NG Repair or replace harness or connector.
OK
Replace heated oxygen sensors
(bank1, 2 sensor1).
9 Perform confirmation driving pattern (See page DI±255).
Go
10 Is there DTC P0171 or P0172 being output again ?
YES Check and replace ECM.
NO
11 Did vehicle runs out of fuel in the past ?
NO Check for intermittent problems.
YES
DTC P0171 or P0172 is caused by running out of fuel.

DI±276
± DIAGNOSTICSENGINE (1MZ±FE)
511 Author: Date:
DTC P0300 Random/Multiple Cylinder Misfire Detected
DTC P0301 Cylinder 1 Misfire Detected
DTC P0302 Cylinder 2 Misfire Detected
DTC P0303 Cylinder 3 Misfire Detected
DTC P0304 Cylinder 4 Misfire Detected
DTC P0305 Cylinder 5 Misfire Detected
DTC P0306 Cylinder 6 Misfire Detected
CIRCUIT DESCRIPTION
Misfire: The ECM uses the crankshaft position sensor and camshaft position sensor to monitor changes in
the crankshaft rotation for each cylinder.
The ECM counts the number of times the engine speed change rate indicates that misfire has occurred.
When the misfire rate equals or exceeds the count indicating that the engine condition has deteriorated, the
MIL lights up.
If the misfire rate is high enough and the driving conditions will cause catalyst overheating, the MIL blinks
when misfiring occurs.
DTC No.DTC Detecting ConditionTrouble Area
P0300Misfiring of random cylinders is detected during any
particular 200 or 1,000 revolutions
Ignition system

Injector

Fuel line pressure
P0301
P0302
P0303For any particular 200 revolutions for engine, misfiring is de-
tected which can cause catalyst overheating
(This causes MIL to blink)

EGR

Compression pressure

Valve clearance not to specification

Valve timing

Mass air flow meterP0303
P0304
P0305
P0306For any particular 1,000 revolutions of engine, misfiring is de-
tected which causes a deterioration in emission
(2 trip detection logic)

Mass air flow meter

Engine coolant temp. sensor

Open or short in engine wire

Connector connection

ECM
DI07S±07

DI±282
± DIAGNOSTICSENGINE (1MZ±FE)
517 Author: Date:
8 Check mass air flow meter and engine coolant temp. sensor
(See pages SF±35, SF±63).
NG Repair or replace.
OK
Check compression pressure, valve
clearance and valve timing.

A03315
Knock Sensor 1
(On right bank)
Knock Sensor 2
(On left bank)EC1 1W
W1
2W
WECM
KNKR
KNKLE1
E1 EC1 1E11
E112827
± DIAGNOSTICSENGINE (1MZ±FE)
DI±283
518 Author: Date:
DTC P0325 Knock Sensor 1 Circuit Malfunction
DTC P0330 Knock Sensor 2 Circuit Malfunction
CIRCUIT DESCRIPTION
Knock sensors are fitted one to the right bank and left bank of the cylinder block to detect engine knocking.
This sensor contains a piezoelectric element which generates a voltage when it becomes deformed, which
occurs when the cylinder block vibrates due to knocking. If engine knocking occurs, ignition timing is retarded
to suppress it.
DTC No.DTC Detecting ConditionTrouble Area
P0325No knock sensor 1 signal to ECM with engine speed between
2,000 rpm and 5,600 rpm.
Open or short in knock sensor 1 circuit

Knock sensor 1 (looseness)

ECM
P0330No knock sensor 2 signal to ECM with engine speed between
2,000 rpm and 5,600 rpm.
Open or short in knock sensor 2 circuit

Knock sensor 2 (looseness)

ECM
If the ECM detects the above diagnosis conditions, it operates the fail±safe function in which the corrective
retard angle value is set to the maximum value.
WIRING DIAGRAM
DI07T±06

A00304
Knock SensorECM
EC1
Male
ConnectorFemale
Connector 1
1
11
22KNKR
KNKL
EC1
E6
E627
28
DI±284
± DIAGNOSTICSENGINE (1MZ±FE)
519 Author: Date:
INSPECTION PROCEDURE
HINT:

DTC P0325 is for the right bank knock sensor circuit. DTC P0330 is for the left bank knock sensor cir-
cuit.

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 Connect OBD II scan tool or TOYOTA hand±held tester, and check knock sensor
circuit.
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand±held tes-
ter to the DLC3.
(b) Disconnect the wire to wire connector EC1.
(c) Connect the terminals of the disconnected EC1 male con-
nector and EC1 female as follows.
Male connector eFemale connector
Terminal 1 e Terminal 2
Terminal 2 e Terminal 1
(d) Turn the ignition switch ON and push the OBD II scan tool
or TOYOTA hand±held tester main switch ON.
(e) After the engine is warmed up, perform quick racing to
4,000 rpm three times.
CHECK:
Check the DTC.
RESULT:
Type IDTC same as when vehicle brought in.
P0325 " P0325 or P0330 " P0330
Type IIDTC different to when vehicle brought in.
P0325 " P0330 or P0330 " P0325