2000 TOYOTA CAMRY test fuel

± DIAGNOSTICSENGINE (5S±FE)
DI±79
314 Author: Date:
DTC P0171 System too Lean (Fuel Trim)
(Only for California Spec.)
DTC P0172 System too Rich (Fuel Trim)
(Only for 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 A/F sensor is approximately proportional to the existing air±fuel ratio, and ECM compar-
ing it with the ideal theoretical value, the ECM reduces fuel volume immediately if the air±fuel ratio is rich
and increases fuel volume if it is lean.
Long±term fuel trim compensates the deviation from the central value of the short±term fuel trim stored up
by each engine tolerance, and the deviation from the central value due to the passage of time and changes
of using environment.
If both the short±term fuel trim and long±term fuel trim exceed 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)

Gas leakage on exhaust system

Air intake (loose hoses)

Fuel line pressure

Injector blockage

Manifold absolute pressure sensor

Engine coolant temp. sensor

A/F sensor
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)

Gas leakage on exhaust system

Fuel line pressure

Injector leak, blockage

Manifold absolute pressure sensor

Engine coolant temp. sensor

A/F sensor
HINT:

When the DTC P0171 is recorded, the actual air±fuel ratio is on the lean side. When DTC P0172 is
recorded, 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 + 38 %, the system
is functioning normally.

The A/F sensor output voltage and the short±term fuel trim value can be read using the OBD II scan
tool or TOYOTA hand±held tester.

The ECM controls the voltage of AF
and AF terminals of ECM to the fixed voltage. Therefore, it
is impossible to confirm the A/F sensor output voltage without OBD II scan tool or TOYOTA hand±held
tester.
DI1JW±03

DI±80
± DIAGNOSTICSENGINE (5S±FE)
315 Author: Date:

OBD II scan tool (excluding TOYOTA hand±held tester) displays the one fifth of the A/F sensor output
voltage which is displayed on the TOYOTA hand±held tester.
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 airÅfuel 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±23).
NG Replace injector.
OK
3 Check manifold absolute pressure sensor and engine coolant temp. sensor
(See pages SF±53 and SF±49).
NG Repair or replace.
OK
4 Check for spark and ignition (See page IG±1).
NG Repair or replace.
OK

DI±82
± DIAGNOSTICSENGINE (5S±FE)
317 Author: Date:
7 Check output voltage of A/F sensor.
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand±held tester to the DLC3.
(b) Warm up the A/F sensor with the engine at 2,500 rpm for approx. 90 sec.
CHECK:
Read voltage value of A/F sensor on the screen of OBD II scan tool or TOYOTA hand±held tester when you
perform all the following conditions.
HINT:
The voltage of AF
terminal of ECM is 3.3 V fixed and AF terminal is 3.0 V fixed. Therefore, it is impossible
to check the A/F sensor output voltage at the terminals (AF
/AF) of ECM.
OK:
ConditionA/F Sensor Voltage value
Engine idling
Engine racing
Not remains at 3.30 V (* 0.660 V)

Not remains at38V(*0 76 V) or moreDriving at engine speed 1,500 rpm or more and vehicle
speed 40 km/h (25 mph) or more, and operate throttle valve
open and close
Not remains at 3.8 V (* 0.76 V) or more

Not remains at 2.8 V (* 0.56 V) or less
*: When you use OBD II scan tool (excluding TOYOTA hand±held tester)
HINT:

During fuel enrichment, there is a case that the output voltage of A/F sensor is below 2.8 V (* 0.56 V),
it is normal.

During fuel cut, there is a case that the output voltage of A/F sensor is above 3.8 V (* 0.76 V), it is nor-
mally.

If output voltage of A/F sensor remains at 3.30 V (* 0.660 V) even after performing all the above condi-
tions, A/F sensor circuit may be open.

If output voltage of A/F sensor remains at 3.8 V (* 0.76 V) or more, or 2.8 V (* 0.56 V) or less even after
performing all the above conditions, A/F sensor circuit may be short.
*: When you use the OBD II scan tool (excluding TOYOTA hand±held tester).
OK Go to step 9.
NG

DI±84
± DIAGNOSTICSENGINE (5S±FE)
319 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)

Gas leakage on exhaust system

Air intake (hose loose)

Fuel line pressure

Injector blockage

Heated oxygen sensor (bank 1 sensor 1)

Manifold absolute pressure sensor

Engine coolant temp. sensor
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)

Gas leakage on exhaust system

Fuel line pressure

Injector leak, blockage

Heated oxygen sensor (bank 1 sensor 1)

Manifold absolute pressure sensor

Engine coolant temp. sensor
HINT:

When the DTC P0171 is recorded, the actual air±fuel ratio is on the LEAN side. When DTC P0172 is
recorded, 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 + 38 %, the system
is functioning normally.

The heated oxygen sensor (bank 1 sensor 1) output voltage and the short±term fuel trim value can
be read using the OBD II scan tool or TOYOTA hand±held tester.
DI4NG±01

± DIAGNOSTICSENGINE (5S±FE)
DI±85
320 Author: Date:
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±23).
NG Replace injector.
OK
3 Check manifold absolute pressure sensor and engine coolant temp. sensor
(See pages SF±53 and SF±49).
NG Repair or replace.
OK
4 Check for spark and ignition (See page IG±1).
NG Repair or replace.
OK

DI±92
± DIAGNOSTICSENGINE (5S±FE)
327 Author: Date:
INSPECTION PROCEDURE
HINT:

If is the case that DTC besides misfire is memorized simultaneously, first perform the troubleshooting
for them.

Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame
data 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.

When the vehicle is brought to the workshop and the misfire is not occurred, misfire can be confirmed
by reproducing the condition or freeze frame data. Also, after finishing the repair, confirm that there
is no misfire. (See the confirmation driving pattern)

When either of SHORT FT #1, LONG FT #1, SHORT FT #2 or LONG FT #2 in the freeze frame data
is besides the range of ±20%, there is a possibility that the air±fuel ratio is inclining either to ºrichº
(±20% or less) or ºleanº (+20% or more).

When COOLANT TEMP in the freeze frame data is less than 80°C (176°F), there is a possibility or
misfire only during warming up.

In the case that misfire cannot be reproduced, the reason may be because of the driving with lack or
fuel, the use of improper fuel, a stain of ignition plug, and etc.
1 Check wire harness, connector and vacuum hose in engine room.
CHECK:
(a) Check the connection conditions of the wire harness and connector.
(b) Check the disconnection, piping and break of the vacuum hose.
NG Repair or replace, then confirm that there is no
misfire (See the confirmation driving pattern).
OK

A00434
± DIAGNOSTICSENGINE (5S±FE)
DI±93
328 Author: Date:
2 Check spark plug and spark of misfiring cylinder.
PREPARATION:
(a) Disconnect the high±tension cord from the spark plug.
(b) Remove the spark plug.
CHECK:
(a) Check the plug type.
(b) Check the electrode for carbon deposits.
(c) Check the electrode gap.
OK:
(a) Platinum±tipped spark plugs with twin ground
electrodes.
Recommended spark plug:
ND made: PK20TR11
NGK made: BKR6EKPB±11
(b) No large carbon deposit present.
Not wet with gasoline or oil.
(c) Electrode gap: 1.1 mm (0.043 in.)
PREPARATION:
(a) Install the spark plug to the high±tension code.
(b) Disconnect the injector connector.
(c) Ground the spark plug.
CHECK:
Check if spark occurs while the engine is being cracked.
NOTICE: To prevent excess fuel being injected from the in-
jectors during this test, don't crank the engine for more
than 5 ~ 10 seconds at a time.
OK:
Spark jumps across electrode gap.
NG Replace or check ignition system
(See page IG±1).
OK

A03598
Knock Sensor 1ECM
KNK
E1 E8 13
W 1
*1: w/o Immobiliser
*2: w/ Immobiliser
(*1) (*2)
E812
± DIAGNOSTICSENGINE (5S±FE)
DI±97
332 Author: Date:
DTC P0325 Knock Sensor 1 Circuit Malfunction
CIRCUIT DESCRIPTION
The knock sensor is fitted to the cylinder block to detect engine knocking. This sensor contains a piezoelec-
tric 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
P0325
No knock sensor 1 signal to ECM with engine speed, 1,200
rpm or more
(2 trip detection logic)
Open or short in knock sensor 1 circuit

Knock sensor 1 (looseness)

ECM
HINT:
If the ECM detects above diagnosis conditions, it operates the fail safe function in which the corrective retard
angle value is set to the maximum value.
WIRING DIAGRAM
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.
DI012±10