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. Interrupted when fault criteria fulfilled or OK reported. Restarts next driving cycle.
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Enable criteria:
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General conditions for this trouble code: When starting the engine, the atmospheric pressure must exceed 78 kPa and the engine coolant and intake air temperatures must exceed -7°C.
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Ignition of catalyst: Engine running. Air mass flow has exceeded 5 g/s (auto. 7 g/s) for 120 s accumulated time. Air mass flow has exceeded 20 g/s for 18 s accumulated time. No engine braking with fuel shut-off for longer than 10 s. No idle period longer than 40 s.
Evaluation of catalyst: More than 200 s elapsed since start. Engine 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 transitions in oxygen sensor 2 corrected with respect to load and engine speed and accumulated during accepted voltage periods for oxygen sensor 1*). When voltage transitions have been corrected and accumulated for 20 s, their mean value will be calculated.
*) Accepted periods have 30-80 % pulse ratio (+trigger).
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Fault criteria:
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Mean value of voltage transitions exceeding a calibrated value.
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Dependents:
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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:
OK report:
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Diagnosis performed once and fault criteria not fulfilled.
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Fault handling:
(See “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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Lead or sulphur in the fuel.
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Functions in the diagnostic tool related to the fault:
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Diagnostic status for the diagnosis.
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See also the description of readings in ”Fault diagnosis, general” for more information.
