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P0420

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: When starting the engine, the atmospheric pressure must exceed 78 kPa and the engine coolant and intake air temperatures must exceed -7C.

- 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.

Assessment of catalytic converter: Longer than 200 sec. since start. Coolant temperature above 70c. Vehicle speed 40-115 km/h. Accelerator pedal depressed. Engine speed 1270-2540 rpm (auto. 1200-2100 rpm). Engine load 140-350 mg/c. Oxygen sensor 2 voltage changes corrected with respect to load and engine speed and accumulated for during approved voltage periods for oxygen sensor 1 *). When the voltage changes have been corrected and accumulated for 20 sec., their average 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, P0116, P0117, P0118, P0131, P0132, P0134, P0138, P0140, P0336, P0337, P0501, P0502, All throttle faults.


System reaction to a fault:


- None.


OK report:


- Diagnosis performed once and fault criteria not fulfilled.


Fault handling: (For more information, see .)


- 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.


For more information, see .