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P0420

Read the instructions below then start the fault diagnostic procedure.

Symptom: CHECK ENGINE.

P0420


Three Way Catalytic Converter. Malfunction.


Fault symptoms


• CHECK ENGINE.


On-Board Diagnostics

Type of diagnosis:


- Once per driving cycle. Interrupted when fault criteria fulfilled or OK reported. Restarts next driving cycle.


Enable criteria:


- General conditions for this trouble code: Atmospheric pressure must exceed 72 kPa and the engine coolant and intake air temperature must exceed -7°C.

- Catalytic converter ignition: Engine running. Mass air flow has exceeded 6 g/s for 120s accumulated time. The mass air flow has exceeded 24 g/s for 18s accumulated time. No engine braking with fuel shut-off longer than 10s. No idling period longer than 40s.

Evaluation of catalytic converter: More than 200 sec. since start. Coolant temperature above 70°C. Speed 40-115 km/h. Accelerator pedal depressed. Engine speed 1100-2300 rpm. Engine load 90-130 mg/c. Voltage transitions in oxygen sensor 2 are corrected with regard to load and engine speed and are accumulated under approved voltage periods for oxygen sensor 1*). When the voltage transitions have been corrected and accumulated for 20 sec their mean value is calculated.

*) Accepted periods have 30-80 % pulse ratio (+trigger).


Fault criteria:


- Mean value of voltage transitions exceeding a calibrated value.


Dependents:


- P0100, P0102, P0103, P0115, P0116, P0117, P0118, P0119, P0131, P0132, P0134, P0138, P0140, P0336, P0337, P0501, P0502, P1133, All throttle faults.


System reaction to a fault:


- None.


OK report:


- Diagnosis performed once and fault criteria not fulfilled.


Fault handling: (See “Fault diagnosis, general” for more information.)


- Type III.


Diagnostic help

The capacity of the catalyst can be reduced temporarily or permanently for the following reasons:


• Lead or sulphur in the fuel.

• Fuel additives.

• Engine oil additives.


Functions in the diagnostic tool related to the fault:


• Diagnostic status for the diagnosis.


See also the description of test values under ”Fault diagnosis, general” for more information.