1999 TOYOTA CAMRY coolant

± DIAGNOSTICSENGINE (1MZ±FE)
DI±259
494 Author: Date:
DTC P0133 Heated Oxygen Sensor Circuit Slow
Response (Bank 1 Sensor 1) (Ex. CA Spec.)
DTC P0153 Heated Oxygen Sensor Circuit Slow
Response (Bank 2 Sensor 1) (Ex. CA Spec.)
CIRCUIT DESCRIPTION
Refer to DTC P0125 (Insufficient Coolant Temp. for Closed Loop Fuel Control) on page DI±244.
DTC No.DTC Detecting ConditionTrouble Area
P0133
P0153
Response time for heated oxygen sensor's voltage output to
change from rich to lean, or from lean to rich, is 1 sec. or more
during idling after engine is warmed up
(2 trip detection logic)

Heated oxygen sensor

Fuel trim malfunction
HINT:
Bank 1 refers to the bank that includes cylinder No.1. Bank 2 refers to the bank that does not include cylinder
No.1. 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 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 P0133, P0153) being output ?
YES Go to relevant DTC chart.
NO
DI4DQ±01

± DIAGNOSTICSENGINE (1MZ±FE)
DI±263
498 Author: Date:
DTC P0135 Heated Oxygen Sensor Heater Circuit Mal-
function (Bank 1 Sensor 1) (EX. CA Spec.)
DTC P0141 Heated Oxygen Sensor Heater Circuit Mal-
function (Bank 1 Sensor 2)
DTC P0155 Heated Oxygen Sensor Heater Circuit Mal-
function (Bank 2 Sensor 1) (EX. CA Spec.)
CIRCUIT DESCRIPTION
Refer to DTC P0125 (Insufficient Coolant Temp. for Closed Loop Fuel Control (Except California Spec.)) on
page DI±244.
DTC No.DTC Detecting ConditionTrouble Area
P0135
P0141
When heater operates, heater current exceeds 2.35 A
(2 trip detection logic)
Open or short in heater circuit of heated oxygen sensor
Htd htP0141
P0155Heater current of 0.2 A or less when heater operates
(2 trip detection logic)
Heated oxygen sensor heater

ECM
HINT:

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

Bank 2 refers to the bank that does not include 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 (Insufficient Coolant Temp. for Closed Loop Fuel Control (Except California Spec.))
on page DI±244.
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.
DI07P±06

± DIAGNOSTICSENGINE (1MZ±FE)
DI±265
500 Author: Date:
DTC P0136 Heated Oxygen Sensor Circuit Malfunction
(Bank 1 Sensor 2)
CIRCUIT DESCRIPTION
Refer to DTC P0125 (Insufficient Coolant Temp. for Closed Loop Fuel Control) on page DI±244.
DTC No.DTC Detecting ConditionTrouble Area
P0136
Voltage output of heated oxygen sensor (bank 1 sensor 2)
remains at 0.4 V or more or 0.6*1 0.5*2 V or less when vehicle
is driven at 50 km/h (31 mph) or more after engine is warmed
up
*
1: for California Spec.
*2: except California Spec.
(2 trip detection logic)

Heated oxygen sensor
HINT:
Bank 1 refers to the bank that includes cylinder No.1. Sensor 2 refers to the sensor farther away from the
engine body.
WIRING DIAGRAM
Refer to DTC P0125 (Insufficient Coolant Temp. for Closed Loop Fuel Control) on page DI±244.
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 heated
oxygen sensor (See page IN±31).
NG Repair or replace harness or connector.
OK
DI07Q±06

± DIAGNOSTICSENGINE (1MZ±FE)
DI±267
502 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 (hose loose)

Fuel line pressure

Injector blockage

Mass air flow meter

Engine coolant temp. sensor

A/F sensors (bank 1, 2 sensor 1)
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

Mass air flow meter

Engine coolant temp. sensor

A/F sensors (bank 1, 2 sensor 1)
DI07R±05

DI±268
± DIAGNOSTICSENGINE (1MZ±FE)
503 Author: Date:
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 + 35 % (80°C (176°F)
or more), the system is functioning normally.

The A/F sensors (bank 1, 2 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.

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

OBD II scan tool (excluding TOYOTA hand±held tester) displays the one fifth of the A/F sensors (bank
1, 2 sensor 1) output voltage which is displayed on the TOYOTA hand±held tester.
INSPECTION PROCEDURE
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±25).
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

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

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