P0420
Read the instructions below then
start the fault diagnostic procedure.
Symptom: CHECK ENGINE.
Three Way Catalytic Converter. Malfunction.
Fault symptoms
On-Board Diagnostics
Type of diagnosis:
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Once per driving cycle. It is interrupted once fault criteria have been fulfilled or OK has been reported. Restarts next driving cycle.
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Enable criteria:
(Conditions that must be fulfilled for diagnostics to be performed.)
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Global conditions for this diagnostic trouble code: When starting the engine, the atmospheric pressure must exceed 78 kPa and the temperature of the coolant and the intake air must exceed -7°C.
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Ignition of catalyst: Engine running. Mass air flow has exceeded 5 g/s (auto. 7 g/s) for an accumulated time of 120s. Mass air flow has exceeded 20 g/s for an accumulated time of 18s. No engine braking with fuel cut-off for longer than 10s. No idling duration longer than 40s.
Evaluation of catalyst: More than 200s since start. Coolant temperature above 70°C. Speed 40-115 km/h. Accelerator pedal depressed. Engine speed 1270-2540 rpm (auto. 1200-2100 rpm). Engine load 140-350 mg/c. Voltage changes for oxygen sensor 2 are corrected with respect to load and engine speed and accumulated during acceptable voltage periods for oxygen sensor 1*). Once voltage changes have been corrected and accumulated during a period of 20s, their mean value is calculated.
*) Acceptable periods have a pulse ratio (+trigger) of 30-80 %.
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Fault criteria:
(When enable criteria have been fulfilled, diagnostics will check if the fault criteria have been fulfilled.)
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Mean value of voltage changes exceeding a calibrated value.
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Dependents:
(Once fault criteria have been fulfilled, a number of other diagnostics must report OK before the diagnostic trouble code can finally be generated.)
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P0100, P0102, P0103, P0116, P0117, P0118, P0131, P0132, P0134, P0138, P0140, P0336, P0337, P0501, P0502, All throttle faults.
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System reaction to a fault:
(Once the fault criteria have been fulfilled, certain measures will sometimes be taken.)
OK report:
(This diagnosis may be included as a dependent to another diagnosis and must therefore report OK even if it is continuous. The OK report is also used in fault handling to count down the fault counter.)
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Diagnosis performed once and fault criteria not fulfilled.
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Fault handling:
(Refer to section “Fault diagnosis, general” for more information.)
Diagnostic help
The capacity of the catalyst can be reduced temporarily or permanently for the following reasons:
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Leaded or sulphurous fuel.
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Diagnostic tool functions related to this fault:
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Diagnostic status for the diagnosis.
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Refer also to the description of readings under ”Fault diagnosis, general” for more information
