Fault Conditions

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.) Initial Inspection and Diagnostic Overview
- 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. Initial Inspection and Diagnostic Overview