Hint
: read freeze frame data using the hand-held tester or the obd ii scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air–fuel ratio was lean or rich, etc. At the time of the malfunction.
1 Check other dtc output(in addition to dtc p0420)
Result:
Hint
: if any other codes besides p0420 are output, perform the troubleshooting for those dtcs first.
2 Check for exhaust gas leakage
3 Inspect heated oxygen sensor(bank 1 sensor 1)
Refer to the hint below.
4 Inspect heated oxygen sensor(bank 1 sensor 2)
Refer to the hint below.
Replace three–way catalytic converter(exhaust manifold)
Hint
: hand–held tester only:
Hint
: ”a/f control” is active test which changes the injection volume –12.5 % Or +25 %.
Result:
heated oxygen sensor reacts in accordance with increase and decrease of
injection volume
+25 % rich output: more than 0.5 V,
–12.5 % Lean output: less than 0.4 V
Notice
: there is a delay of few seconds in the sensor 1 (front sensor) output, and there is about 20 seconds delay at maximum in the sensor 2 (rear sensor).
The following of a/f control procedure enables the technician to check and graph the voltage outputs of both the heated oxygen sensors.
For displaying the graph indication, enter ”active test / a/f control / user data”, then select ”o2s b1s1 and o2s b1s2” by pressing ”yes” button and push ”enter” button before pressing ”f4” button.
Circuit description
The intake air temperature (iat) sensor, mounted on the mass
air flow (maf) sensor, monitors the intake air temperature. The
iat sensor has a thermistor that varies its resistance depending
on the temperature of the intake air. When the air temperature
is low, the resistance in the thermisto ...
Check open circuit
For the open circuit in the wire harness in fig. 1, Perform
a resistance check in step (b) or a voltage check in step
(c) to locate the section.
Check the resistance.
Disconnect connectors a and c and measure the
resistance between them.
Resistance: 1 Ω or les ...
Check and replace ecu
Notice:
start an inspection of the connector from the backside
of the connector on the wire harness side with
the connector connected to the ecu.
When no measurement condition is specified, perform
the inspection with the engine stopped and also
the ignition switch on.
First check the ec ...