O2 sensor TOYOTA CAMRY 2000 Service Repair Manual

DI±102
± DIAGNOSTICSENGINE (5S±FE)
337 Author: Date:
3 Inspect sensor installation and teeth of crankshaft timing pulley
(See pages IG±10 and EM±15).
NG Tighten the sensor. Replace crankshaft timing
pulley.
OK
Check and replace ECM (See page IN±31).

± DIAGNOSTICSENGINE (5S±FE)
DI±103
338 Author: Date:
DTC P0340 Camshaft Position Sensor Circuit
Malfunction
CIRCUIT DESCRIPTION
Camshaft position sensor (G signal) consist of signal plate and pickup coil.
The G signal plate has one tooth on its outer circumference and is mounted on the exhaust camshaft.
When the camshafts rotate, the protrusion on the signal plate and the air gap on the pickup coil change,
causing fluctuations in the magnetic field and generating an electromotive force in the pickup coil.
The NE signal plate has 34 teeth and is mounted on the crankshaft. The NE signal sensor generates 34
signals for every engine revolution. The ECM detects the standard crankshaft angle based on the G signals
and the actual crankshaft angle and the engine speed by the NE signals.
DTC No.DTC Detecting ConditionTrouble Area
P0340
No camshaft position sensor signal to ECM during cranking
(2 trip detection logic)
Open or short in camshaft position sensor circuit

Camshaft position sensor
Di t ib tP0340No camshaft position sensor signal to ECM with engine speed
600 rpm or more
Distributor

Starter

ECM
WIRING DIAGRAM
Refer to DTC P0335 (Crankshaft Position Sensor ºAº Circuit Malfunction) on page DI±100.
DI014±09

DI±104
± DIAGNOSTICSENGINE (5S±FE)
339 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 resistance of camshaft position sensor (signal generator)
(See page IG±1).
Reference: INSPECTION USING OSCILLOSCOPE
Refer to DTC P0335 (Crankshaft Position Sensor ºAº Circuit Malfunction) on page DI±100.
NG Replace camshaft position sensor.
OK
2 Check for open and short in harness and connector between ECM and camshaft
position sensor (See page IN±31).
NG Repair or replace harness or connector.
OK
3 Inspect sensor installation and tooth of camshaft timing pulley
(See pages IG±9 and EM±17).
NG Tighten the sensor. Replace camshaft timing
pulley.
OK
Check and replace ECM (See page IN±31).

P25430
ECM
Throttle Body
EGR
Vacuum
Modulator EGR Valve
VSV
Exhaust Gas Throttle
Valve
u
± DIAGNOSTICSENGINE (5S±FE)
DI±105
340 Author: Date:
DTC P0401 Exhaust Gas Recirculation Flow Insufficient
Detected
CIRCUIT DESCRIPTION
The EGR system recirculates exhaust gas, which is controlled to the proper quantity to suit the driving condi-
tions, into the intake air mixture to slow down combustion, reduce the combustion temperature and reduce
NOx emissions. The amount of EGR is regulated by the EGR vacuum modulator according to the engine
load.
If even one of the following conditions is fulfilled, the VSV is
turned ON by a signal from the ECM.
This results in atmospheric air acting on the EGR valve, closing
the EGR valve and shutting off the exhaust gas (EGR cut±off).
Under the following conditions, EGR is cut to maintain driveabil-
ity.

Before engine is warmed up.

During deceleration (throttle valve closed).

Light engine load (amount of intake air very small).

Engine idling.

Engine speed over 4,400 rpm.

High engine load (amount of intake air very large).
DTC No.DTC Detecting ConditionTrouble Area
P0401
After engine is warmed up, intake manifold absolute pressure
is larger than value calculated by ECM while EGR system is
ON
(2 trip detection logic)

EGR valve stuck closed

Open or short in VSV circuit for EGR

Vacuum or EGR hose disconnected

Manifold absolute pressure sensor

VSV for EGR open or close malfunction

ECM
DI015±05

± DIAGNOSTICSENGINE (5S±FE)
DI±109
344 Author: Date:
4 Check EGR system (See page EC±12).
NG Repair or replace.
OK
5 Check EGR vacuum modulator (See page EC±12).
NG Repair or replace.
OK
6 Check EGR valve (See page EC±12).
NG Repair or replace.
OK
7 Check manifold absolute pressure sensor (See page SF±53).
NG Repair or replace.
OK
Check and replace ECM (See page IN±31).

DI±112
± DIAGNOSTICSENGINE (5S±FE)
347 Author: Date:
7 Check manifold absolute pressure sensor (See page SF±53).
NG Repair and replace.
OK
Check and replace ECM (See page IN±31).

± DIAGNOSTICSENGINE (5S±FE)
DI±113
348 Author: Date:
DTC P0402 Exhaust Gas Recirculation Flow Excessive
Detected
CIRCUIT DESCRIPTION
Refer to DTC P0401 (Exhaust Gas Recirculation Flow Insufficient Detected) on page DI±105.
DTC No.DTC Detecting ConditionTrouble Area
P0402
After engine is warmed up, conditions (a) and (b) continue:
(a) Intake manifold absolute pressure is larger than value cal-
culated by ECM while EGR system is ON
(b) Misfiring is detected during idling
(2 trip detection logic)
EGR valve stuck open

Vacuum or EGR hose is connected to wrong post

Manifold absolute pressure sensor

ECM
WIRING DIAGRAM
Refer to DTC P0401 (Exhaust Gas Recirculation Flow Insufficient Detected) on DI±105.
SYSTEM CHECK DRIVING PATTEM
Refer to DTC P0401 (Exhaust Gas Recirculation Flow Insufficient Detected) on DI±105.
INSPECTION PROCEDURE
HINT:

If DTC P0105 (Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction), P0106 (Manifold
Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem) and P0402 (Exhaust
Gas Recirculation Flow Excessive Detected) are output simultaneously, perform troubleshooting of
DTC P0105 first.

If DTC P0401 (Exhaust Gas Recirculation Flow Insufficient Detected) and P0402 (Exhaust Gas Recir-
culation Flow Excessive Detected) are output simultaneously, perform troubleshooting of DTC P0402
first.

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 connection of vacuum hose and EGR hose (See page EC±12).
NG Repair or replace.
OK
DI016±04

± DIAGNOSTICSENGINE (5S±FE)
DI±115
350 Author: Date:
6 Check EGR vacuum modulator (See page EC±12).
NG Repair or replace.
OK
7 Check manifold absolute pressure sensor (See page SF±53).
NG Repair or replace.
OK
Check and replace ECM (See page IN±31).

FI7081
Waveform of Heated Oxygen
Sensor before CatalystNormal CatalystWaveform of Heated Oxygen
Sensor behind Catalyst DI±116
± DIAGNOSTICSENGINE (5S±FE)
351 Author: Date:
DTC P0420 Catalyst System Efficiency Below Threshold
(Except California Spec.)
CIRCUIT DESCRIPTION
The ECM compares the waveform of the heated oxygen sensor located before the catalyst with the wave-
form of the heated oxygen sensor located behind the catalyst to determine whether or not catalyst perfor-
mance has deteriorated.
Air±fuel ratio feedback compensation keeps the waveform of the heated oxygen sensor before the catalyst
repeatedly changing back and forth from rich to lean.
If the catalyst is functioning normally, the waveform of the heated oxygen sensor behind the catalyst switches
back and forth between rich and lean much more slowly than the waveform of the heated oxygen sensor
before the catalyst.
But when both waveforms change at a similar rate, it indicates that catalyst performance has deteriorated.


DTC No.DTC Detecting ConditionTrouble Area
P0420
After engine and catalyst are warmed up, and while vehicle is
driven within set vehicle and engine speed range, waveforms
of heated oxygen sensors (bank 1 sensor 1, 2) have same
amplitude (2 trip detection logic)
Three±way catalytic converter

Open or short in heated oxygen sensor circuit

Heated oxygen sensor
DI1JX±03

FI7132
Engine Speed
2,500 ~ 3,000 rpm
Idling
IG SW OFF
Warmed up3 min. or soCheck
Time (a)(c)
(d)
(b)
FI6514
OX Signal Waveform (Oscilloscope)
1.0 V
0 V
200 msec. /Division
± DIAGNOSTICSENGINE (5S±FE)
DI±117
352 Author: Date:
CONFIRMATION ENGINE RACING PATTERN
(a) Connect the TOYOTA hand±held tester to the DLC3, or connect the probe of the oscilloscope between
terminals OX1, OX2 and E1 of the ECM connector.
(b) Start engine and warm it up with all accessories switched OFF until water temp. is stable.
(c) Race the engine at 2,500 ~ 3,000 rpm for about 3 min.
(d) After confirming that the waveforms of the heated oxygen sensor (bank 1 sensor 1 (OX1)), oscillate
around 0.5 V during feedback to the ECM, check the waveform of the heated oxygen sensor (bank
1 sensor 2 (OX2)).
HINT:

If there is a malfunction in the system, the waveform of the
heated oxygen sensor (bank 1 sensor 2 (OX2)) is almost
the same as that of the heated oxygen sensor (bank 1
sensor 1 (OX1)) on the left.

There are some cases where, even though a malfunction
exists, the MIL may either light up or not light up.