Fault code description - three-way catalytic converter effectiveness too low

AD07.61-P-4000-16L

Fault code description - three-way catalytic converter effectiveness too low

Engine 137.970



1

Fault code

( Readout on generic scan tool)

P200B The effect of the catalytic converter for cylinders 1 to 3 is insufficient.(P0422)

P207E The effect of the catalytic converter for cylinders 4 to 6 is insufficient.(P0422)

P20A3 The effect of the catalytic converter for cylinders 7 to 9 is insufficient.(P0432)

P20A4 The effect of the catalytic converter for cylinders 10 to 12 is insufficient.(P0432)

2

Fault storage

Actuation of engine diagnosis indicator lamp (EURO4)

or CHECK ENGINE (MIL) malfunction indicator lamp 

after expiry of test duration and fault

following two successive driving cycles with faults

3

Checking frequency

once per driving cycle

4

Checked signal or status

O2 sensor signal downstream of TWC

5

Fault setting conditions

Limit value

Checking duration

The effective O2 sensor signal downstream of TWC must not be greater than a constantly calculated reference signal.

Approx. 30 seconds

6

Check prerequisites

- engine speed approx. 1400 to 2100 rpm

- lambda control enabled

- no fault in O2 sensors (signal, heater, aging)

- no high loading of activated carbon filter (lambda greater than 0.4)

- no misfiring

- no fault in secondary air injection

- no fault in leaktightness of purge system 

- load 20 to 50% (12 kg/hour to 150 kg/hour), for cylinder shutoff 30 to 70%

- catalytic converter temperature greater than 480°C

7



The TWC is evaluated according to its ability to store oxygen. The oxygen stored during a lean-mixed phase is either completely or partially consumed during a rich-mixed phase. The storage capacity and thus also the HC conversion are reduced through aging.

If the fault codes for the TWC and for the O2 sensors are issued identically, the O2 sensors should be replaced. If then a TWC fault is no longer detected, and if the effect of the three-way catalytic converter has been slightly reduced, it does not need to be replaced yet.